San Francisco | Elon Musk celebrated his 44th birthday in July 2015 at a three-day party thrown by his wife at a California wine country resort dotted with cabins. It was family and friends only, with children racing around the upscale property in Napa Valley.

This was years before Twitter became X, and Tesla had a profitable year. Musk and his wife, Talulah Riley – an actress who played a beautiful but dangerous robot on HBO’s science fiction series Westworld –were a year from throwing in the towel on their second marriage. Larry Page, a party guest, was still CEO of Google. And artificial intelligence had pierced the public consciousness only a few years before, when it was used to identify cats on YouTube – with 16 per cent accuracy.