With an $852 billion valuation, OpenAI is one of the world’s most valuable startups. But unlike many Silicon Valley CEOs, Sam Altman’s fortune isn’t tied to his AI company’s soaring valuation.

Altman notably owns no equity in OpenAI and has historically taken a salary of roughly $76,000 a year. Even so, Altman has amassed a net worth of more than $3.3 billion, and in a recent interview, Altman credited venture capitalists Peter Thiel and Paul Graham with teaching him the investing philosophy that helped shape his multibillion-dollar portfolio.

“I really learned from Peter Thiel and Paul Graham, both in two different ways, which is that the very best companies, the very best investment opportunities are almost never the ones that look really popular,” Altman said on the Invest Like The Best podcast in an episode released last week.

“You can do OK just following the trend of being a little early, but to do spectacularly well, you almost always have to do things that are not what everybody else is doing. You cannot be following the new wave.”

Altman has put that approach into practice throughout the 41-year-old’s two decades in Silicon Valley. He and his venture funds have stakes in some 400 companies, according to the Wall Street Journal, including early bets on Reddit, Airbnb, and Stripe. Forbes added that one of his largest investments is a $1.65 billion stake in nuclear fusion firm Helion, which he first invested in around 2015.