Garry Tan says turning down Peter Thiel's early offer to join Palantir was a $2-4 billion 'mistake'

Y Combinator CEO Garry Tan said he turned down an offer to be on Palantir's founding team.

Bloomberg/Getty Images Garry Tan said he once passed up a role on Palantir's founding team to stay at Microsoft.

It was a "$2-4 billion mistake," he said.

He learned not to chase "what was hot." Tan eventually joined Palantir as its 10th employee.

He now leads startup accelerator Y Combinator.

Garry Tan was employee No.

10 at Palantir.

He regrets that it wasn't single digits.

On " The A16z Show ," the Y Combinator CEO said that he was offered a place on the company's founding team — but he turned it down to stay at Microsoft.

Tan was in Stanford University's Phi Kappa Psi fraternity.

His frat brothers included Joe Lonsdale and Stephen Cohen, two Palantir cofounders.

Both were interning at Peter Thiel's hedge fund, Tan said.

He described one of Thiel's strategies: "When you start a thing, you write down on a piece of paper all the smartest people who you need to go and hire." Tan was on both of their lists, he said.

So, Tan said that Lonsdale and Cohen flew him down from Seattle to have dinner with Thiel.