It turned out the next Google — at least in terms of the wealth it generated — was Facebook, in which Mr. Thiel was an investor. It was less than two miles away.

“If I had to give that talk again, I’d say there was far less than a 50 percent chance that it’s in a 50-mile radius,” he said. Perhaps the next great company would be in China, he suggested; perhaps elsewhere in the United States.

The natural concentration of the tech industry was always an odd thing.

“These technologies enabled globalization. They were about destroying the tyranny of place,” he said. “It was a bit paradoxical that the overwhelming majority of them emerged in this very small place.”

There are other reasons to leave. As the valley has gotten bigger and richer, it has, he feels, grown more close-minded.

Sam Altman of Y Combinator, the start-up accelerator, is a friend of Mr. Thiel’s. He said the investor had a point. “Silicon Valley has lost some of its ability to tolerate controversial ideas that sometimes create a lot of value,” he said.