A few days before planning to flee the U.S. for good, Mr. Ding was arrested. After an 11-day trial in January, a federal jury convicted the 38-year-old engineer on seven counts of economic espionage and seven counts of theft. He was sentenced to nearly a year in prison.

Mr. Huang seemed to have had a similar carefree attitude toward his relationship with Ms. Huang, as if he wouldn’t be caught, and if he were, it wouldn’t matter. With his power and wealth and importance, that was probably true — until it wasn’t.

Regis McKenna is the grand old man of Silicon Valley, who came here in the early 1960s when it was still apricot orchards. The tech industry then was an arm of the defense industry, and pioneers like Gordon Moore and Robert Noyce had a Midwestern, almost military rectitude. Mr. McKenna, a marketer who worked for America Online, Apple, Genentech, Lotus, Microsoft and other companies, had dinner plans when I called. He only had time for one question.

Does too much money —

“Yes, yes,” he interrupted. “Does it turn their heads, does it turn their morals? Yes. Money changes people, and it started changing Silicon Valley a long time ago.”

In just a few days, if all goes as planned, will finally come the Anthropic public offering. How big a deal is it? In 1999 and 2000, the peak years of the dot-com boom, 800 companies went public. Their combined value on their first day of trading will likely be less than Anthropic, according to calculations by the finance expert Jay Ritter.

Never have so few made so much so fast. The world will be in awe. Look for some of these technologists to believe their press coverage, shrug off any natural caution and, in the great tradition of Silicon Valley, do something transcendently stupid.

John Markoff contributed reporting.