I fell out of love with London on the A2 outside Greenwich. The tower blocks rose like teeth from the horizon, shrouded on a clear day in brown-grey vapour – stale coffee breath of the overworked capital. Queuing for the Blackwall Tunnel gives you time to contemplate the perversity of it all: drumming the steering wheel, cursing the other drivers, jostling for position on the tarmac tongue of the beast, competing to be swallowed first.

The approach used to be exhilarating and comforting at the same time, the electric thrum of reconnection to the national power source combined with the security of home. And to call London home felt, as Cecil Rhodes once said of being born British, like winning first prize in the lottery of life. The city’s credentials as a global hub are beyond doubt: the diversity, the history, the old cultural pedigree, the new cultural ingenuity, the attitude, the pace, the permissiveness, the ambition, the money…

The only question was whether London was peerless; was the article definite – the global city. Others spread wider and pack in more people, but those are banal scales. London’s bigness is transcendent. It sees only New York as a rival, with Paris respected as a veteran of the game, past its prime.

As for the rest of Britain, London’s supremacy is untouchable by other cities and extreme by international standards. It accounts for around 22% of UK GDP and around 19% of employment. Since 2010, 79% of new private-sector jobs have been generated by the capital.

‘London’s supremacy is untouchable by other cities’: Rafael Behr considers the capital’s unique charms. Photograph: Adina Tovy/Getty Images

Like all snobberies, London-centrism is variegated. The inner-zone dwellers look down on the suburbs; the born-and-bred natives look down on newcomers. I was delivered into the capital at University College Hospital near St Pancras in 1974. There were a few years at university and a stint as a foreign correspondent abroad, which seemed to confirm that most other places, while possessed of unique charms, could correct their deficiencies by being more like London.

Departure was involuntary: the London we loved turned its back on us before we decided to leave

But I am not a Londoner any more. I quit last year; or went into recovery. I now live with my family in Brighton, which is a coastal exclave of pseudo-London urbanity – a place where jaded addicts of megacity life wean themselves clean; metropolitan methadone.

Here the ex-Londoners display years of service on globalisation’s front line like campaign medals. When asked where we live, we cannot help working the fact that we used to live in London into the answer. It is a trait of exile: the feeling that departure from the homeland was involuntary; that the London we loved turned its back on us before we decided to leave.

This is an affectation for people like me who have sold a house in London to finance the move elsewhere. Ours is not a hard-luck story. The real exiles are families whose rent is covered by housing benefit, tipping their nominal income from benefits over the level of the government cap of £500 per week. That excludes any family property in central London. Council tenants with spare rooms have also been hit by the “bedroom tax”. Estimates of the total number forced to move by combined changes in the social security regime over the past five years are disputed, ranging from a few thousand to tens of thousands. The Department for Work and Pensions says people are responding to work incentives, seeking new lives elsewhere; the opposition calls it social cleansing.

‘Drumming the steering wheel, cursing the other drivers’: queuing for traffic gave Rafael Behr time to contemplate the perversity of living in London. Photograph: Graeme Robertson

The underlying problem is the chronic housing shortage. Estate agents, politicians and policy experts agree that London needs 40-50,000 new homes every year to compensate for generations of shortfall. Last year 18,260 were completed – up 2% on the previous year. That which is built must also be affordable, but demand still gallops ahead of supply. So, in accordance with the oldest law in economics, prices go berserk. The average deposit required to buy in the capital is £70,000, which leaves two ways to get on to the ladder: one is to be extremely rich, the other is to be quite rich and then borrow more money than you could ever repay.

The rest rent. The amount they pay has increased at rates far outstripping national inflation at a time when wages have stagnated. It is now common for tenants to pay well over half of their income on housing before feeding, clothing and heating themselves. It is hardly surprising that increasing numbers consider that a bad deal. The prospect of eking out a family life in a windowless shoebox is driving some 30-somethings out of the capital. There will always be new arrivals to replace them. The opportunities are magnetic enough to draw in successive generations of ambitious youth, not least from overseas, although the rate of churn will increase. No doubt the next Google is being cooked up by whip-smart kids in a Shoreditch tech-lab right now, although I’ll bet some of their start-up capital (not to mention their rent) is from the bank of Mum and Dad.

Historically migrants, internal and foreign, would arrive in the inner city and graduate to leafier parts as their incomes increased. That trend is reversing as central properties become more desirable. In the future there will be a hereditary class of central Londoners employing a financially precarious, casual labour force commuting in from the outskirts, grinding out a low-paid existence, noses pressed against the glass of the glitzy quarters. It is a process described by Alan Ehrenhalt, a US author and chronicler of urban trends, as “the great inversion” – a transition from the 20th-century model of poor downtown boroughs surrounded by affluent suburbs to a 21st-century pattern of exclusive enclaves and poor migrants encamped on the periphery.

It starts with a vanguard class of young creative types reclaiming zones of social and economic dereliction, setting up what Ehrenhalt sardonically describes as “projects through which a small coterie of local artists seek to display their sheer edginess to one another”. The hipster pioneers are followed by young couples with bourgeois-bohemian sensibilities – what the French call “bobo” – who breed and fill the pavements with space-age prams. I was that cliché once, wheeling my daughters around Hackney in the gentrificational transition between murder rates falling and Foxtons arriving on the high street. Then come the really wealthy types who like urban edge fully blunted by waves of demographic change. Before you know it a draughty three-bedroom Victorian terraced house in what was once a slum costs more than £1m.

Home economics: London prices are driving many out of the capital. Photograph: Yui Mok/PA

It isn’t just the housing that costs too much. London is barely affordable on every measure. When inflation is factored in, median pay fell from £700 per week in 2010 to £646 last year. There is an army of employees on minimum wage and zero-hour contracts who get up before the rest of the capital to lubricate its commercial wheels. Heading in for an early editing shift I used to sit with the cleaners and sandwich-makers on the last night bus before early-morning timetables had even started, sharing seats with saucer-eyed clubbers wringing the last kicks from the night before.

A middle-class exodus is what happens when your city becomes a global reserve currency

Stark inequality isn’t new in the big city, although the trends point to widening extremes. Research by Danny Dorling and Benjamin Hennig of Oxford University’s School of Geography and Environment, over three decades of census data, identifies an hourglass shape in London’s income distribution – bulging at the top and bottom. The number of poor households and very rich ones has risen by 80%; the middle has shrunk by 43%.

Alongside the material deprivation is cultural exclusion. A lot of Londoners effectively live below-stairs, servicing the capital for the minority, the value they add measured by how inconspicuous they can make themselves. But even the relatively well-heeled aren’t comfortable in the city, because there is always someone wealthier nearby to provoke pangs of inadequacy. The upper- middle classes, objects of envy from below, struggle to keep up with the oligarchic Joneskis who set the pace for elite London living.

‘I quit last year; or went into recovery’: Rafael Behr heads for the coast. Photograph: Suki Dhanda for the Observer

The capital has always had an aristocracy, but in the past decade or two the familiar British elite – hereditary and self-made – has been eclipsed by the global super-rich. London is a great place to be opulent, not just because of the shopping but because of the tax-efficient real estate opportunities. By the standards of most developed countries, Britain hardly dares to tax expensive property at all; council-tax rates in poor boroughs are higher than in rich ones. In 2012, when most of the UK was economically stagnant, £83bn worth of properties were purchased in London without financing; in other words no mortgage, no deposit, no scrimping. Cash.

Not all of that is pocket money of the international jet set, but some of it is. There are also the local multimillionaires, the hedge-fund managers and bankers. That the City generates wealth for London and the UK is undeniable. There is also a cost in contamination by the ethos of swaggering hauteur; the attitude that sees humility as an evolutionary cul-de-sac.

Ultra-affluence brings its own peculiar kind of dislocation, palpable in places like Chelsea and St John’s Wood, that were always well-off but, in the city I grew up in, used to feel more securely woven into the fabric of the place. The gilded class is more segregated now, gazing out from behind tinted glass and security-coded gates. Observing the change, the American writer Michael Goldfarb has described the defining feature of London’s globalised age as transience – a decay of that visceral allegiance that makes life in a big city tolerable as a shared experience. “I wonder whether those just parking their money here by buying real estate will ever be able to provide the communal sensibility to help the City survive the inevitable shocks it will experience in years to come,” Goldfarb wrote in 2013. He foresaw an exodus of middle-class professionals heading elsewhere in search of a family-friendly lifestyle that would be not just more affordable but more soulful. “This is what happens when your city becomes a global reserve currency.”

Before you know it a draughty Victorian terraced house in what was once a slum costs more than £1m

Danny Dorling warns of the UK becoming a resort for the jet set: “London takes the role that Mayfair had in the past, where the gentry came in for the season. The same could happen on a global scale with the global gentry.” This model is not without benefits. “Everyone in the top 1% probably generates about six jobs,” notes Dorling. “They need nannies, cleaners, maybe chauffeurs. But in that scenario we do get a hollowing out.” People in the middle skip town.

My case is not exceptional. There is a well-established trend dating back to the 1970s of people hitting early middle age, having children and fleeing. Many would probably leave earlier if they didn’t feel bullied by that insidious Dr Johnson quote into sticking it out. Tired of London; tired of life? No. Never. Actually, yes, tired of living in the belly of the beast.

‘Metropolitan methadone’: Brighton, says Rafael Behr, is ‘where megacity addicts wean themselves clean’. Photograph: Graham Turner for the Guardian

The escape impulse is primitive. It is an appetite for oxygen, a dream of kids having a free-range childhood and a desire to see the horizon for sustained periods. There is no better symbol of London’s macho financialisation than the early 21st-century surge in skyscraper construction, the lanky delinquent mob of new towers that cluster around the City, and their gangmaster, the Shard. It looks like Darth Vader’s imperial Star Destroyer erupting through the crust of a Bermondsey pavement. It is easy to be impressed by such a sight, but no one could be seduced by it. Awe is what despots seek because they cannot nurture affection. Intimidation breeds obedience and even a craven kind of attachment, but never tenderness. London used to win people with charm; now it controls them with fear.

To truly belong in a place means loving even the things about it that are unlovely. The real British patriot has a secret fondness for summer rain – the pathos of the season that fails heroically. London patriotism means relishing the crowds, the noise, the surliness and the grime. Where outsiders see mechanistic bustle, insiders feel exhilarating anonymity, the gift of invisibility through dissolution in the throng. There is also a discreet London solidarity, imperceptible to the naked eye. Newcomers think the city is unfriendly. Veterans know it is just frugal with gestures; unsentimental but not callous.

Or it used TO be like that. It is hard to know whether my relationship with the capital died because it changed or I did. Probably both. I romanticise an early phase of life frittered away in 90s London as part of a generation that graduated with modest debts and moved into affordable flats on the cusp of a fin-de-siècle boom. It is easy to extrapolate from a solipsistic, carefree youth a false memory that there was less worth caring about. Nostalgia is the cushion that age slips under its opinions when taking a rest from evidence. Grotesque mutations come quicker to the imagination – are easier to write about – than slow metamorphoses. London might just settle into a different groove. Sometimes obnoxious behaviour turns out to be only a phase. “When something is as extreme as London, the most expensive place in rich world, the most likely trajectory is change; that it will one day no longer hold the top slot,” says Dorling. “But you can’t predict what the change will be.”

I’m clearly not alone in feeling London’s chaotic exuberance has soured into a dysfunctional mania. What was once eccentricity now feels like a pathology. It was certainly unhealthy for me, which is why I left. I didn’t belong any more, which could be just my problem, or it could be that feelings of alienation are intrinsic to a London syndrome – a sense that the cultural sinews binding the city together have stretched too far; that ever fewer people feel they truly belong there or that the capital belongs to them, to us. It is the centre of wealth and power in the UK, but its rule is not benign. Without rivals to challenge them, rulers turn tyrant.

Nicola, writer, and Rollo, computer programmer, both 29

Left London for Snowdonia in September 2012

Broadband refugees: all Nicola and Rollo need to work is a fast internet link – and Wales is lovely and inexpensive.

We initially moved here for six months to get out of the city for a bit, but we’ve stayed nearly three years. We’re just outside a tiny village with no shop or pub, and the nearest town is a 20-minute drive away. As long as we have fast internet, we can work anywhere. We have no history in Snowdonia – I’m from Wokingham, Rollo from Devon – but we wanted to move somewhere rural. The rent is half what we paid in London. We had a studio flat there, and here we have a two-bedroom cottage, with mountain and coastline views. We loved our London flat, but it was a bit squashed. We used to hold a book club and everyone would sit and have cheese and biscuits on our bed. Now we’ve settled in and made friends with our neighbours, who have taught Rollo woodwork: he made my engagement ring. I care about the environment, and it felt mad to be campaigning for green issues in London and not enjoying the benefits of the natural world. Now I can walk up a mountain, swim in a lake, or go to the sea – it’s lovely. For our London friends it’s a novelty, so most weekends we’ve had visitors; we haven’t felt cut off. We don’t want to go back to the city.

Nick, architect, 33

Left London for Newcastle in April 2015

Grim down south: architect Nick can afford gym fees now he’s back in Newcastle. Photograph: Alex Telfer for the Observer

A lot of people like me had to move to London because of the recession. I’m from Newcastle and when I graduated in architecture there were no jobs up here. I lived in a box room in a shared flat in Clapham for a year and a half, then in Hampstead for a year with a girlfriend who earned more than me, and then I paid over £700 a month, before bills, for a room in Hackney. In the meantime, my friends back home had already bought a place, and were selling that to move to a nice Victorian house. I did look at buying in London, but even stretching myself financially there’s no way I could afford somewhere big enough to settle down and have kids. But in the last year or so firms up here have started to appoint again. Now I’m working for a multi-award-winning practice and my career hasn’t suffered at all. I can eat out whenever I like here, and I also have a car and have joined a gym, which I couldn’t afford in London. You forget how green it is here; when you come to Newcastle from London it’s like someone’s applied an Instagram filter. I miss some of the friends I made in London, the famous architecture, and my dodgeball team. You can’t play dodgeball in Newcastle! Ideally I’d like to build my own house. In London, the cost of the land is too high, but up here it’s possible.

Ruth, baker, 31

Left London for Berlin in December 2014

Ich bin ein Berliner: Ruth, right, with her partner, still dreams of opening a café in London one day. Photograph: Steffen Roth for the Observer

After three years working at a publishing company in London, I left my job to start a small baking business. It went quite well, but I wasn’t able to properly support myself as London is so expensive. My dream is to start a café and in London I was looking at start-up costs of hundreds of thousands of pounds. I was living with my boyfriend at the time and I went to Berlin for a weekend. I met a woman there, and fell in love with her. I spent a year in London breaking up with my boyfriend and decided to go to Berlin to see what was possible for the business – I’d spent two years and all my savings on it, so that was a real deciding factor. The food scene in Berlin is still quite underdeveloped, so if you’re doing something well by London standards, it’s quite easy to stand out here. Now I have several regular clients. It’s much easier to survive on less money here and the options to develop my business are much more realistic. My plan is to open my café within the next year. When things are well established here, it might be possible to go back to London and open a café there. Things are changing in Berlin, though: people like me coming from places like London are making Berlin more expensive. Berlin has recently become the first European city to introduce a rent cap. That should be introduced in London, too. KATIE FORSTER