Mr. Thiel prides himself on his elaborate parties, and his inauguration event, held in his seven-bedroom home, included a hired juggler who rather than juggling, instead posed trivia questions to guests about U.S. presidents. Snack cakes and other appetizers were passed around, and larger bites were served at stations. (The Mar-a-Lago station had shrimp, steak and salad with Thousand Island dressing; there was also a food delivery from McDonald’s.) Gift bags were filed with small bottles of Moët champagne. There were, of course, red MAGA hats.

Prominent tech industry guests, among a heavily male list, included Sam Altman, the chief executive of OpenAI, the crypto investors Cameron and Tyler Winklevoss, and after a brief period of haggling with security over the guest list, Alexandr Wang. Mr. Wang, who runs one of the most celebrated artificial-intelligence startups in the world, ScaleAI, was able to talk his way into the mansion, which Mr. Thiel purchased several years ago from Wilbur Ross, Mr. Trump’s former commerce secretary. Joe Osborne, a company spokesman, said Mr. Wang had been temporarily unable to get in because the event was at capacity.

Silicon Valley’s politics have trended to the right since Mr. Trump’s election, and many of the main personalities of that movement were seen at the Thiel party. Guests included the tech podcasters Chamath Palihapitiya, Jason Calacanis and David Friedberg, hosts of the “All-In” show with Mr. Sacks; former Uber chief executive Travis Kalanick; incoming administration officials such as Jacob Helberg, Ken Howery and Sriram Krishnan, all from Silicon Valley; and Senators Bill Hagerty, Ted Cruz and Dave McCormick.

House Speaker Mike Johnson described the party as “a lot of fun,” with the best part being “the company.” Senator Ted Cruz, who has worked to cultivate a relationship with Mr. Thiel over the years, said this was not, in fact, the best part of the weekend. That, he said, “is gonna be noon on Monday.”