Up in San Francisco’s Monterey Heights district stands a modest detached house; a house that would be perfectly ordinary, were its wide windows not covered in neon green scribbles — half-finished equations, anatomies of computer architecture. They are marks left by the coders who use this place as a hide-out.

The troupe of five or so developers, clad in hoodies and jeans, have an air of Peter Pan’s lost boys. They may be young — in their early to mid-twenties — but these programmers are the heart of the most extraordinary financial story of recent months: cryptocurrencies, digital tokens with no intrinsic value, suddenly worth billions. I’m here to meet the coders’ leader, Vitalik Buterin, the Russian-Canadian creator of Ethereum, arguably the most successful of the hundreds of copycat cryptocurrencies to have emerged in the seven years since bitcoin rose to prominence. On the damp, overcast morning earlier this year when I take a Lyft car (an Uber equivalent) to his San Francisco headquarters, Ethereum’s market value was some $125bn — second only to bitcoin.

Once I’ve squeezed past his earnest acolytes, the angular young man I recognise from tech conference stages shakes my hand gingerly, his fingers flattened. With hollow cheeks and downy brown hair, he is more mathematics prodigy than tech magnate.

We had booked a fancy Mexican restaurant in San Francisco’s Latin-inflected Mission district, but at the last minute I was told he would prefer a quiet takeaway here at Ethereum’s San Francisco home-from-home. He’s dressed in a loose canary yellow T-shirt featuring a cartoon character, black tracksuit trousers and a watch with a pink plastic strap. Its face is a cat, whose transparent Cheshire grin exposes the mechanism. I ask for his precise age. He answers without hesitation: “23.96”.

It was his father Dmitry, also a computer scientist, who first introduced his son to the idea of blockchain and cryptocurrency. He had encouraged his son to build video games from the age of 10. Then in 2011 he told him about bitcoin. Created two years earlier as the world reeled from the failures of the banking system, bitcoin lets people exchange cash online without a bank mediating the transaction. Bitcoin’s enigmatic creator remains unidentified, but among its godfathers were cypherpunks: hackers dedicated to privacy, determined to undermine authorities who led us to the financial crisis.

There’s projects that never had a soul, that are just like, ra-ra, price go up. Lambo[rghini], vrromm, buybuybuy now!

The then 17-year-old Vitalik initially dismissed the idea, but then did his own research into virtual money. Soon he was writing articles — paid for in bitcoins — while studying computer science at Canada’s University of Waterloo, eventually leading him to co-found Bitcoin Magazine. Back in 2011, bitcoin was considered so radical many believed governments would ban it, pointing to the dark market it supported. Yet it survived, trading at highs of $19,000 at Christmas, although a crash followed.

A blockchain is “an interesting and new kind of organism” Buterin says after we have slid across floorboards through the open-plan living room to a wooden dining table. That is something of an understatement, I think. Simply put, a blockchain is a ledger stored across thousands of computers. Spreading the record out this way, and securing it with Byzantine mathematics called cryptography, makes it harder to tamper with than traditional information hoards. Centralised data troves, such as your brain, are liable to lose things — and, as Equifax found via the hacking of its customer data files, are vulnerable to attack. By contrast, blockchain ledgers are open for all to read and not controlled by a single entity.

Buterin’s particular genius was to see the potential to create a blockchain of his own, Ethereum, that other services could build on, from payments to games. It quickly grew a life of its own, with everyone from scientists to banks and entrepreneurs clamouring to build on it. Aged just 19, Buterin quit university to guide it.

We both make for a bench; after some awkward hovering, he folds his bony frame into a chair. We dither about food. I suggest tacos or pizza. His collaborator, Thomas Greco, a developer who says he has worked with Buterin for years, suggests Thai. Before I have time to find a menu on my phone, Greco has whizzed through options for nearby Chaiya Thai Restaurant and is ordering with his thumb.

Buterin is the first to admit he had a weird 2017. Entrepreneurs building on Ethereum started using it to mint fresh coins to crowdfund virtual money for their ventures, a novel funding mechanism called initial coin offerings. Bitcoin and ether prices rocketed and ICOs exploded — but fuelled fears of tulip-style mania. “We’ve created a culture where some totally random project raising something like $8m is like, oh yeah that’s peanuts,” he says. “You know you’re in a bubble!”

The rising ether price has made him a multi-millionaire but unlike bitcoin believers who have tended stubbornly to hold the asset, he was never confident cryptocurrencies would catch on. When prices looked right, he’d cash in — and he has “financially paid dearly for it”, he remarks, cheerfully, estimating his paper wealth would be three to four times higher had he sold less cryptocurrency. After years at $1 to $100, bitcoin jumped from under $1,000 in January 2017 to over $19,000 by December (the ebullience leaked out of the market, however — it’s now about $8,000).

Buterin is under pressure to translate breathless blockchain excitement into results. He rapidly explains his efforts to improve Ethereum, which recently jammed under the strain of people swapping virtual cats in a game called CryptoKitties, where players breed and swap digital felines. The scaling initiatives have names such as “sharding”, “state channels” and “plasma”. I’m relieved when we switch to simpler stuff — such as his desire for immortality.

Buterin has pondered eternal life since he was a child. Not long after his family emigrated from Russia when he was six, he stumbled on a book by Aubrey de Grey, a controversial British scientist with radical ideas to defeat ageing. Why does he want to live forever, I ask as we sip green tea made by Greco, while waiting for our food. Buterin is “kind of puzzle[d] as to why this is even a question”. If you could live forever, he reasons, choosing not to is “the equivalent of jumping off a cliff”. He later reassures me that while life extension solutions have been slow coming they could be ready by 2060, which is “probably enough for you”. (I’m 25.)

Chaiya Thai Restaurant 272 Claremont Blvd, San Francisco, CA, 94127 Tamarind prawns $14 Pad pak with tofu $10 Green curry $10 Brown rice x2 $6 Green tea x2 No charge Total (inc tax and delivery) $50.56

So what would he do with eternal life, I ask, imagining he might yearn to crack unsolved mathematics proofs. Not quite. “The most important thing is to enjoy it,” he replies. During flights, he practises the languages he’s not yet fluent in by watching French, German or Chinese films.

As we talk, cryptocurrency is having something of a cultural shift. The idealistic early coders, who wanted blockchain to transfer power from corporations and governments to individuals, last year started getting overtaken by get-rich-quick schemers. Some ICOs were scams. Buterin watched in dismay as his blockchain was flooded by mercenaries making a fast buck.

“There’s projects that never had a soul, that are just like, ra-ra, price go up,” he flaps his long hands, “Lambo[rghini], vrromm, buybuybuy now!” Then he blurts out a critique of the digital token, Tron, breaking the tension by laughing uproariously. Tron’s market valuation hit $17bn without any discernible product.

The outlandish valuations are, he says, “far ahead of what this space has actually accomplished for the world”.

Even as we wait for delivery, the crypto markets are tanking. By the end of the day, ether will have crashed 30 per cent. This volatility would have traders sweating, but it’s nothing to crypto-veterans such as Buterin — he doesn’t even check his phone.

The boom may disillusion Buterin, but he has welcomed mainstream investment in blockchain. The Ethereum Enterprise Alliance was founded in 2016 to test enterprise uses for the blockchain — members range from BP to JPMorgan. The EEA reflects Buterin’s changing mindset. As a teenager, he shared the rebellious crypto-community’s common attitude: “the system”, ie governments, banks and major corporations, “is basically evil, and we needs [sic] to outright resist it and build a new thing” (Buterin has a childlike tic, incorrectly adding “s” to some verbs).

But he came to realise these people “aren’t that different from people anywhere else”. Purists might call this betraying blockchain’s roots; Buterin paints it as pragmatism, coloured with anxiety about governments with “hundreds of billions of dollars of physical weaponry, plenty of prisons . . . increasing amounts of internet surveillance”.

[E]ven if your goal is to overthrow parts of the establishment, you want to have and present an image of why this is driving human progress

Buterin has cause to fret: he watched early bitcoiners who used bitcoin for drug trafficking get caught. He cites Ross Ulbricht, the impossibly young American libertarian who ran dark web market Silk Road, an illegal online marketplace for illicit substances and goods, largely on bitcoin. Ulbricht’s infamous decision to hire hit men rewrote the narrative of bitcoin, argues Buterin, turning a story about “possibly a civil disobedient martyr” to “actual criminal and a public enemy”. Now in his early thirties, Ulbricht last year lost a five-year court battle and faces life in prison.

“[E]ven if your goal is to overthrow parts of the establishment, you want to have and present an image of why this is driving human progress,” he explains. “[The] Lord of the Rings and Star Wars could give people a very, very misleading impression of social conflict”. His reference to hobbits and jedis invoke a child’s morality, righteousness versus evil; Buterin has adjusted to a world without clear-cut villains and heroes.

So who’s the most significant person in his life? For once he’s silenced. “Hmmm.” Pause. “It’s hard to think of one single person. Yeah.” We’re saved by the delivery’s arrival.

Two women on sofas are tapping at sticker-covered laptops. The atmosphere is student house, pre-finals exams. Buterin fetches plates and forks (but not knives). We unwrap spiced prawns and vegetable pad pak for him; absinthe green vegetable curry with brown rice for me.

I ask what he remembers about Russia, which he left aged six. Peeling the prawn shells with long, nail-bitten fingers, he recites facts about his hometown, Kolomna: population 140,000; 115km from Moscow. He visited Moscow and St Petersburg last year, meeting Vladimir Putin, and is talking to Russian officials about a cryptorouble project. He has explained he’s establishment-friendly these days, but I have trouble understanding why he’d help an authoritarian government. He paraphrases Frederick Douglass, who was criticised for engaging with slaveholders but said: “I would unite with anyone to do right; and with nobody to do wrong”.

He later confides he’s encouraging the Kremlin to deliver “crypto-y benefits for the people”, but adds, despondently, that he’s “not sure how much of that is actually getting through”.

Willingness to talk has propelled Buterin on a seemingly open-ended diplomacy tour. In the past month, he’s visited four countries, Thailand, Singapore, China, the US. He has no fixed address. “Right now I’m basically just floating everywhere,” he says. So, where does he leave his stuff while he’s travelling? He races from the room. Baffled, I fork at some aubergine. He returns with a bright pink duffel bag, overflowing with T-shirts. Doesn’t he own books? He gestures to his Android phone.

When his fortune grew from $1m to over $10m-$20m (for once he fudges the numbers), he didn’t feel “yay I get more stuff; it’s more certainty that I won’t have to worry about money for a long time”. He donates to the Gates Foundation, GiveDirectly, and De Grey’s anti-ageing SENS Research Foundation.

His most important influence, he says, is the internet, and last June it killed him off: a viral rumour that he was dead knocked $4bn in market cap off ether, revealing how integral cryptocurrency traders see Buterin to Ethereum. “It’s like OK, wow, that’s weird,” he recalls. “My family members were sending me WeChat messages saying, are you OK?”

I notice shadows under his piercing blue eyes. For all his public appearances, his celebrity does not sit easily.

“Last year it got to the point where [the fame] got more annoying than good,” he says. He recalls a man trailing him around an aeroplane and through an airport, trying to talk to him.

Was this something he wanted, this leadership position? He doesn’t miss a beat. “No.” So how did it happen? “Mmmm. Ethereum got big.” He hangs his head, like I’d scolded him. “[It] just so happened that Ethereum evolved without, I guess, other figures quite as large as myself.”

Buterin seems downcast. Attempting to lighten the mood, I ask where he’d like to be in five years’ time. “I have no idea,” he sighs. “I generally don’t plan more than three months ahead, let alone five years.” It’s clear that Ethereum started as a project, not a career plan. He ridicules the bitcoin millionaires who’ve ridden the crypto-tsunami to riches, flaunting it as investment prowess.

“It’s the luck of the draw, where everyone who won the draw seems to feel like they deserved it for being smarter,” rants Buterin. He impersonates a bitcoin bull: “I was loyal and I was virtuous and I held through and therefore I deserve to have my five mansions and 23 lambos!” We laugh.

Having polished off the prawns, he picks up food granules with his index finger and describes walking through a rundown district in China recently. He fixates on the “scrappy grocery stores, with five-year-old kids helping mommy and daddy rearrange the water bottles.” They reminded him that “these are the people you’re actually serving”.

I can sense Buterin itching to get back online. He removes the plates and thanks me for coming. I step into the grey day, a good distance from anywhere and without having called a car. Since the tradition is that the FT pays, I left $45 in notes for Greco, but discovered belatedly I was $5 short. Don’t worry, Greco tells me later over email. I can pay him the difference in ether.

Chloe Cornish is an FT graduate trainee reporter, covering European capital markets from London

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