When you work in customer service, one of the best ways to pass the time is by speculating about the inner lives of your clientele. Is table three’s relationship at its beginning, middle or end? What is the cause of the lingering enmity between two grown-up siblings buying their aged mother an expensive perfume?

The game is even more fun if you work in a bookshop, as I did for many years on and off before becoming a journalist. Few things provide you with more glimpses into someone’s inner life than the books they buy.

The only problem with bookselling is that one of the most popular genres – self-help – ruins the game. If a couple visit the shop together regularly and then, seemingly overnight, one half of the pairing starts coming in on their own and buying a lot of romantic fiction, there are several possible reasons. But there is nothing coded about buying self-help: the clue is in the title.

Self-help is to most bookshops as the slave trade was to the British Empire: the inhabitants deplore it and don’t want to acknowledge it, but they are also guiltily conscious that it balances the books and keeps the show on the road. Booksellers dislike the genre, not just because it takes the fun out of speculating baselessly about the lives of one’s customers, but because it ruins the joy of repeat sales. Seeing someone who comes in to buy a single book leave with an extra recommendation – and return for more when they’re finished – is one of the job’s greatest pleasures, whether “more” means another history of the Second World War, an experimental novel or a spy thriller.

Selling a person more than one self-help book, however, makes you feel less like a bookseller and more like a con man. I’m certain that the authors of Think Yourself Rich, The 7 Habits of Highly Effective People and Rich Dad Poor Dad all believe what they’re saying, but from my experience, one of the habits of highly effective people is that they don’t buy books about how to get rich.

What does this have to do with politics? Well, shortly after the election of Donald Trump, it emerged that there was a large overlap between people who posted online frequently in support of the new American president (and various far-right ideas) and those who visited “pick-up artist” or PUA message boards, where men exchange tips about how best to pick up women. The foundational text of the PUA community is The Game by Neil Strauss, a book of which I sold more copies than I care to count. It includes such advice as wearing an outlandish hat so that women will notice you and come to discuss it, and tells readers to “neg” their dates – give them backhanded compliments that make them feel insecure.

The tragedy of The Game is that it doesn’t work: the single men who buy it learn a series of toxic behaviours and slide further into loneliness and misery. That can eventually lead them to radicalisation of one flavour or another. Yes, there is a lot to dislike about self-help. Publishers seem to feel the same way about the genre as booksellers, and many hive off their lucrative self-help titles to a separate imprint to keep their catalogues pure. But from time to time, a self-help book somehow acquires a patina of respectability and intrudes, however briefly, on the national conversation. One such title is Canadian psychology professor Jordan Peterson’s 12 Rules For Life: An Antidote to Chaos, currently selling faster than a Jeremy Corbyn poster at Labour party conference, and published by serious non-fiction outlet Allen Lane. The astonishing sales aren’t novel for the genre, but the elite approval is. In the New York Times, columnist David Brooks dubbed Peterson the “most influential public intellectual in the Western world right now”.

When I worked in a bookshop, I always used to make a point of reading every book we sold in great numbers, to see what the fuss was about. That means I’ve read more self-help than I care to think about, and so 12 Rules For Life left me with an overpowering feeling of déjà vu. It’s the usual collection of banalities, commonplace advice dressed up as forbidden wisdom.

Admittedly, the anecdotes from the author’s professional life – an essential element of the genre – are given a greater respectability because Peterson’s day job is being an academic psychologist at the University of Toronto. The book contains grandiose claims designed to sell routine psychological well-being to the kind of man who might otherwise sneer at “self-care”. One section sums up the vibe: a series of interminable pages about reproduction in lobsters and what this “proves” about how men and women relate to each other, followed by the innocuous but important advice to keep to a regular sleep pattern and carry yourself with confidence.

The reason so many commentators are talking about this book, then, isn’t because of its literary merit or the usefulness of its content. It’s because Peterson’s most vocal fans are the same men who moved from exchanging tips about how best to pick up women to tweeting about how wonderful Trump is. Peterson has 695,000 subscribers on YouTube, where videos such as “Identity politics and the Marxist lie of white privilege” and “Introduction to the Idea of God” receive hundreds of thousands of views.

The good thing about Peterson’s book is that, unlike The Game or most of the stuff I sold, if readers follow its strictures, they will feel a little bit better. It is that rare thing: self-help that might actually be helpful.

At the bookshop, we disliked self-help books because their buyers stopped being objects of speculation and were revealed to us as vulnerable fellow humans. Peterson’s success reminds us that pick-up artists and young, radicalised white men online are vulnerable, too – even while they persist in voting and acting in ways that result in very real dangers for everybody else.