There is a suspense embedded in Michael Lewis’ account of the rise and fall of Sam Bankman-Fried that makes an already fascinating book more delicious. As followers of the collapse of the crypto king’s empire will know, halfway through the writing of the book, the author’s task changed dramatically from profiling one of the world’s youngest billionaires to charting his spectacular implosion. Bankman-Fried’s cryptocurrency exchange, FTX, is bankrupt and he is now appearing in a Manhattan federal court on multiple charges of fraud. In Going Infinite, the suspense is less rooted in whether or not he is guilty than whether Lewis will ever stop being so thoroughly charmed by him.

I should say here that I love Michael Lewis. As with all of his writing – with the exception of a toe-curling profile he did of President Obama for Vanity Fair 11 years ago – Going Infinite is insanely readable and I devoured it, marvelling at Lewis’s ability to pace, structure and humanise a story about something as dense and unfriendly as crypto. Two seconds after finishing I couldn’t have told you a single thing about how bitcoin actually works. It doesn’t matter. As with previous outings such as Moneyball (nerdy baseball stats), The Big Short (credit default swaps), and Flash Boys (high-frequency trading), Going Infinite shows off Lewis’s peculiar genius for making arcane information as transporting as fantasy fiction.

There is a difference between Going Infinite and Lewis’s earlier titles, however, and that is the reliability of the book’s protagonist. When the author meets Bankman-Fried in late 2021, he is a 29-year-old billionaire who, as one Silicon Valley venture capitalist tells Lewis, has a shot at becoming the world’s “first trillionaire”. At the time, Bankman-Fried is living in the Bahamas, running FTX and a hedge fund called Alameda Research, and trying to figure out how to use his billions to save the world. He is exactly Lewis’s kind of hero, a brilliant young man and maths savant whose mental acuity is exceeded only by his social unease, and in the opening pages Lewis describes him, fondly, as scruffy, unassuming and “a bit odd”. “His ambition was grandiose,” writes Lewis, “but he wasn’t.” And there it is, the book’s central tension. For the next 250 pages, I found myself wondering if, with this generous assessment, Lewis had made the right call.

There are, essentially, two books unfolding within Going Infinite, the first a straightforward romp through Bankman-Fried’s life that delivers at the level of pure entertainment. His parents are both law professors at Stanford, crunchy academics who don’t see the need to celebrate birthdays or encourage their clever child in the delusion of Santa Claus. He doesn’t fit in at school and only finds his crowd later, first at summer maths camp, then at MIT, and finally, after landing his first job at a secretive and exclusive trading company called Jane Street Capital, among the other financial traders. So perfectly suited is Bankman-Fried to high-stakes trading that, after six months, his superiors at Jane Street inform him that if he sticks with it, in a decade he could be making $75m a year.

As it turns out, this forecast is conservative. Within a year, Bankman-Fried has outgrown conventional trading and quit Jane Street to co-found his own hedge fund, Alameda, recruiting a skeleton staff from among old pals from maths camp and MIT. When he sees bigger opportunities in the wild west of crypto trading, which no Wall Street bank can or will touch, he sets up FTX in the Bahamas and starts turning profits that make his salary at Jane Street look like the minimum wage.

This part of the book is very jolly indeed, jammed with nuggets that remind one just how good Lewis is at winning the trust of his subjects. When Bankman-Fried settled on the Bahamas as a location for his business, he wondered, idly, if he should pay off the country’s $9bn national debt to improve its infrastructure so workers for FTX wanted to move there. When Elon Musk’s purchase of Twitter was going through, Bankman-Fried tells the author he messaged one of Musk’s financial advisers saying he’d be willing to invest $5bn if Musk moved Twitter on to a blockchain. (This didn’t happen). He considered offering Donald Trump $5bn not to run for president. And so it goes on, the spectacle of what happens when an impulsive young man has access to almost limitless resources. As Bankman-Fried’s wealth and fame grow, so do the bizarre encounters, until one night in LA he is button-holed by Katy Perry, who wants to talk to him about crypto – at which point, I found myself thinking that even without jail, the man has suffered enough.

Lewis tells the story of Bankman-Fried’s swashbuckling rise with predictable brio, but there is another, trickier side to the tale and here, Lewis struggles. He tries to get around the huge question mark over his subject’s character by telling an opaque parable about a man called Bob – the moral of which is do we ever, really know our friends – but it doesn’t disguise the fact that Lewis can’t bear to think ill of his subject. Early on in the book, Bankman-Fried falls under the influence of a group of young philosophers from Oxford who espouse a set of ideas they call Effective Altruism. One of them, William MacAskill, poses a question to Bankman-Fried that resonates throughout his subsequent actions: “What if I became an altruistic banker, pursuing a lucrative career in order to donate my earnings?” Bankman-Fried takes up this philosophy, becomes a vegan and throws himself into becoming rich enough to save the world. This is the story as he tells it and Lewis accepts it, entirely.

From the evidence presented, it does seem that Bankman-Fried isn’t motivated by personal, material gain. Self-enrichment doesn’t interest him beyond the gamer’s urge to beat the house and defeat his opponents. The absence of lavish spending, however, is not in itself evidence of the simplicity of motive Lewis ascribes to him. Bankman-Fried believes life’s only sensible philosophy is utilitarianism, which, he tells the author, scares most people because it “encourages selflessness”. But on the evidence of the book, Sam Bankman-Fried is not particularly selfless.

In fact, a lot of the time, he appears to be a monstrous arsehole whose wealth and fame enable behaviours, professional and personal, that wouldn’t otherwise be tolerated. Twice, Bankman-Fried moves countries to flee a girlfriend asking for slightly more commitment from him. “I’m sorry I’m so shitty to date,” he writes in a memo to her. It seems to occur neither to Bankman-Fried nor the author that one way to be less shitty to date might be to have a stab at behaving less shittily.

The 31-year-old’s behaviour in business is no better. He repeatedly breaks important commitments at the last minute, humiliating his team. When he sets up Alameda, he denies equity to everyone else in the company and, when $4m in funds briefly goes missing, fails to inform customers. The money shows up, eventually – its disappearance is down to a software glitch – but not before his colleagues have accused him of terrible management, arrogant decision making and effectively lying to customers.

Bankman-Fried does not believe himself to be lying, here or anywhere else. (In court, he has pleaded not guilty to all charges). “Fault,” he says, “is just a construct of human society.” Later in the book, he tells a colleague that when under pressure to answer a question he doesn’t like, he just throws a “word salad” at it or pivots to something else. The fraud charges, which were brought last year, hinge on $8bn of customer funds being allegedly transferred from FTX for use by Alameda, which only came to light after the collapse of crypto caused a run on the exchange. One feels for Lewis having to reassess, mid-project, someone he clearly likes and respects. My question would be why he regarded Bankman-Fried with such indulgence in the first place.To this point, I found myself thinking increasingly of Michael Oher, another of Michael Lewis’s protagonists, who featured in The Blind Side, his bestseller of 2006 that was later made into a Hollywood film. Oher, a Black American from an impoverished background who went on to become a star of American football, is now embroiled in a conflict with the white couple who “adopted” him and claims that The Blind Side traduced and belittled him. Both Oher and Bankman-Fried are, to some extent, characterised as childlike by Lewis, but in only one of these men is that childishness presented as a rakish side-effect of brilliance.

In fact, to use a word Bankman-Fried is fond of applying to other people, he often behaves in a way that is straightforwardly “dumb”. When implementing his altruistic philosophy, he resolved to avoid sloppy human sentiment in favour of data – to ensure, as Lewis states admiringly, that “what mattered was the math”. As it turns out, this wasn’t a reliable metric. Other things mattered more.