The Trump whom Mr. Thiel touted at the Republican convention was a candidate who would “end the era of stupid wars and rebuild our country,” move us past “fake culture wars” and start projects the equivalent of the Apollo space program. That does not seem to be the president he got. “There are all these ways that things have fallen short,” Mr. Thiel said. But he said he had no regrets about his endorsement. “It’s still better than Hillary Clinton or the Republican zombies,” he said, referring to the other candidates. The White House did not respond to a request for comment. Mr. Thiel is routinely labeled a libertarian. On a bookshelf in the apartment, as if in confirmation, is a hardback copy of Ayn Rand’s “Atlas Shrugged,” the bible of the movement. A gift, he said. A lesser-known but possibly deeper influence was the French philosopher René Girard, who taught at Stanford University when Mr. Thiel was an undergraduate there. For 15 years, on and off, Mr. Thiel sat in on a study group about Mr. Girard’s ideas. Mr. Girard believed human beings were deeply mimetic, which is to say they copy one another. “It’s very anti-Ayn Rand: There are no self-contained autonomous figures,” Mr. Thiel said. “Our desires are not our own. They get shaped powerfully by the society around us.” It was this illumination that helped him see the potential of Facebook — where people could find out in intimate and addictive detail what their friends were up to — when it was barely a year old. He was the first outside investor, buying 10 percent of the company for $500,000. He sold most of his holdings in 2012 as Facebook went public. A few months ago, with Facebook’s market capitalization at about $500 billion, he sold most of what he had left. Last summer, there was a flap when a memo by a fellow board member, Reed Hastings, the chief executive of Netflix, appeared in The New York Times. In the memo, Mr. Hastings wrote to Mr. Thiel that he displayed “catastrophically bad judgment” in