"Liar's Poker" and "The Undoing Project" author Michael Lewis. Business Insider

Michael Lewis' "Liar's Poker" has been a must-read for anyone who works on or cares about Wall Street since it was first published in 1989.

It captures Lewis' time spent as a young bond salesman at Salomon Brothers from 1984 to 1989. This is the same wild period immortalized in Oliver Stone's classic 1987 film "Wall Street," but Lewis' memoir focuses on the comedic side of the rough and sometimes dark world of loosely regulated finance.

Three decades and one massive recession later, the Wall Street of today is unrecognizable from the one Lewis inhabited.

"What's happened to Wall Street since 'Liar's Poker' came out is that its relationship with the rest of society has become much more problematic," Lewis told Business Insider in a recent interview about current events and his new book, "The Undoing Project."

"It's become cagier, more guarded, closed, and afraid of how it seems to the wider world," he said. "More political."

In a 2012 video for Big Think, Lewis said he saw Wall Street start to clean up its act — superficially speaking — about the time "Liar's Poker" came out, as more firms went public and felt compelled to rid themselves of the profanity and blatant misogyny Lewis describes so well in his book. He added, however, that while most Wall Streeters began behaving better in these public firms through the 1990s and the early 2000s, they felt freer to make reckless investments with other people's money, which led to the subprime-mortgage crisis of 2007-2009.

It's in the wake of the Great Recession bailouts that Wall Street became politicized, Lewis said. He said he was afraid the incoming Trump administration's proposed rollback of market regulations could lead to another crisis for these "too big to fail" banks.

As far as the outlandish young investment-bank culture in which Lewis once found himself, there is poll evidence it's no longer as appealing to fresh college talent as it used to be. Lewis thinks that might change in a Trump presidency, if he commits to deregulation.

"If you're the kind of kid who thinks that all that's important in life is making money, it's probably still the place to go, especially now that Trump's elected," Lewis said. "In Wall Street now, you have to hide what you're doing. It's more fun when you don't have to do that. But I don't think its sense of purpose has changed at all."

Lewis' assessment of Wall Street may be generally pessimistic, but he said hope lies in young people like IEX founder Brad Katsuyama, the protagonist of his 2013 book "Flash Boys." The catch is that the talent that wants to take a path based on ideals, like Katsuyama's dedication to eradicating unfair advantages derived from abuses of high-frequency trading, will make less money than its less idealistic peers.

"You find great purpose there, but you may not find great profits when the game you're playing is making a living by reducing the size of Wall Street, sucking some of the revenues out of it, and reducing the tax the financial-sector levies on the rest of the economy," Lewis said. "You're not going to get rich doing that like you get rich figuring out how to increase the tax."