GEOFF BENNETT: The man at the center of a major fraud trial in New York right now, Sam Bankman-Fried, is also the subject of a new book by the bestselling author Michael Lewis.

Our economics correspondent, Paul Solman, talked with him about his new book called "Going Infinite" and the reaction to a story that changed dramatically as he was writing it.

So, how many interviews this week?

MICHAEL LEWIS, Author, "Going Infinite": Oh, actually, not that bad, because we just kind of skipped cable television, but maybe 20.

PAUL SOLMAN: Still, Michael Lewis was a bit hoarse and has in the past few weeks himself become the subject of considerable blowback for his book's nonjudgmental portrayal of its much-reviled crypto hero, or antihero, Sam Bankman-Fried, on trial for defrauding investors, allegedly diverting billions for his personal use.

Can you boil down who Sam Bankman-Fried is succinctly?

MICHAEL LEWIS: Sam Bankman-Fried is a child of two academics from Stanford, California, who discovered a peculiar gift for Wall Street trading after he comes out of MIT and sees in the crypto markets an opportunity to make a whole bunch of money, which he says he's going to give away.

PAUL SOLMAN: To causes that fund effective altruism.

What is effective altruism?

MICHAEL LEWIS: Earn to give, that, rather than extend yourself in a heartful way to something you do, like, I don't know, go be a doctor in Africa and cure kids of blindness or prevent kids from going blind or saving lives, you go to Wall Street, you make a fortune, and you pay 50 doctors to Africa.

It's like, the math works.

And it's that idea that hooked Sam.

PAUL SOLMAN: And both his parents were proponents, are proponents of utilitarianism, right, the greatest good for the greatest number?

MICHAEL LEWIS: Yes, think of the son taking the parents' loose ideas and pushing them to an extreme.

PAUL SOLMAN: And so Bankman-Fried began amassing his supposed-to-do-good fortune.

MICHAEL LEWIS: And, in a period of about two years, goes from having zero dollars to having, according to "Forbes" magazine, $22.5 billion.

PAUL SOLMAN: How exactly?

The super nerd savant leaves Wall Street and starts his own private hedge fund, Alameda, trading cryptocurrencies like Bitcoin, but mainly dozens of less famous ones like APT, XRP, SCG, whose prices supposedly differed on different markets long enough that Alameda could buy and sell instantly and make a fortune, playing in the crypto casino.

But, fatefully, says Lewis: MICHAEL LEWIS: He realizes for a bunch of reasons that there's more money to be made owning the casino, rather than trading in the casino.

And he starts alongside the trading firm, this crypto exchange called FTX.

PAUL SOLMAN: FTX was supposed to be like any exchange, taking money from customers, depositors, to buy the crypto coins they're investing in.

Good business.

MICHAEL LEWIS: Very simple business.

It's an exchange business.

It's like you have got $250 billion of crypto being traded every month on your exchange, and you're taking a small fraction of all that, and you just -- you make a fortune.

And venture capitalists had valued this business at $40 billion.

PAUL SOLMAN: Almost all of which the young man now known as SBF owned.

Lewis loved the business, met SBF, told a friend to invest, invested himself, and, to write a book, became Sam's companion, didn't think he was shadowing a con man, but: MICHAEL LEWIS: What happens over the course of several years is, a whole bunch of money that's meant to be on the exchange and owned by the depositors on FTX ends up in his private trading firm.

And this gets discovered when FTX depositors last November start demanding their money back in droves, and it's not there.

KATE ROONEY, CNBC: FTX went from a $32 billion company to bankruptcy in a matter of just four days or so.

PAUL SOLMAN: Instead, Alameda, the trading fund, was, according to its CEO, Caroline Ellison, using it, at SBF's direction, to buy and sell crypto.

And with a new haircut for court, Sam's also been attacked for using FTX's money to fund effective altruists, Democrats and non-Trump Republicans, shower multimillions on condos in the Bahamas and on marketing, stadium naming rights, celebrity towels.

SHAQUILLE O'NEAL, Former NBA Player: Hey, it's Shaquille O'Neal, and I'm excited to be partnering with FTX to help make crypto accessible to everyone.

PAUL SOLMAN: Tom Brady.

TOM BRADY, Former NFL Player: I'm trading crypto.

FTX is the safest and easiest way to buy and sell crypto.

It's the best way to get in the game.

PAUL SOLMAN: Even grouchy Larry David.

ACTOR: Like I was saying, it's FTX.

It's a safe and easy way to get into crypto.

PAUL SOLMAN: Doing much of this with depositors' money, which would be criminal.

And the prosecution has gotten two top lieutenants, SBF's computer coder and Ellison, the former girlfriend who ran Alameda, to testify.

So how naive was Lewis when Brad Katsuyama, the now-rich friend he'd made famous in an earlier book, "Flash Boys," asked Lewis to check Sam out?

MICHAEL LEWIS: My friend said: "Do you smell a rat?"

And I said: "No."

"What could go wrong?"

is what I said.

PAUL SOLMAN: But you were utterly charmed by him, right?

I mean.. MICHAEL LEWIS: I was -- you know, I don't know.

I still like him.

PAUL SOLMAN: How close did you get to him, do you think?

Too close maybe?

MICHAEL LEWIS: My relationship with him was virtually identical to the relationships I have with all the subjects of my book.

If I'm going to describe you well, I have to be able to see your life.

PAUL SOLMAN: But to many now following the trial, Lewis hasn't been nearly open enough in denouncing his subject's dishonesty.

MICHAEL LEWIS: There is a small group of people who are very loud who would rather me just join a lynch mob.

And that's not my job.

My job is to, like, learn as much as I can, tell the story as I see it, and let the reader figure out what they make of it.

PAUL SOLMAN: Are you kind of taken aback by how you have become so much of the story?

MICHAEL LEWIS: That will pass.

People who dislike Sam Bankman-Fried, right -- and a lot of people do -- their first impulse is to dislike the fact I have even written a book about Sam Bankman-Fried.

And if it doesn't -- if the narrative in the book is in any way more nuanced than the narrative in their head, they don't like that either.

I often hope to feel that with the material I'm given to make a book out of, that it's so good, I'm only constrained by my literary powers.

And, in this case, this seemed like it rose to the level of Greek tragedy or Shakespeare.

PAUL SOLMAN: Or, to many tracking the trial, sank to the level of simple fraud.

But, either way, it sure hasn't hurt book sales, the most Lewis has ever had in a first week, he says, more than 100,000, with plenty to come.

And the film rights were sold before publication for $5 million.

Sam Bankman-Fried is still worth real money, it seems, as a subject.

For the "PBS NewsHour," Paul Solman.