Following Tuesday night’s election victory of democratic socialist Zoran Mamdani as New York City’s mayor,an email Thiel sent five years ago went viral.

In the correspondence to Mark Zuckerberg, Marc Andreessen and others, he warned that “When 70% of Millennials say they are pro-socialist, we need to do better than simply dismiss them by saying that they are stupid or entitled or brainwashed; we should try and understand why.”

Thiel expanded on those concerns in an interview with the Free Press that was published on Friday, saying strict zoning laws and construction limits have benefited boomers, who have seen their properties appreciate, but have harmed millennials, who struggle to buy homes.

“If you proletarianize the young people, you shouldn’t be surprised if they eventually become communist,” he explained.

While Thiel, who backed Donald Trump’s re-election, disagrees with Mamdani’s solutions to New York’s housing affordability problems, he credited the lawmaker for discussing the issue more openly than establishment figures.