Sam Altman’s escape from the Silicon Valley pack is a sprawling farm at the end of a road that snakes through the vine-swept hills in Napa Valley. I spot the 40-year-old with slightly tousled hair in the open-plan kitchen of the wide bay-windowed house, and I step right in. His bemused look tells me that I wasn’t expected. I am, it turns out, nearly an hour early, but the man behind ChatGPT will finish up a meeting and join me in the garden. I wait under a grapevine-shaded pergola that runs along the house. Since OpenAI, the company he runs,...