In early 2018, the founders of Chinese artificial intelligence startup SenseTime Group Ltd. flew to Tokyo to see billionaire investor Masayoshi Son. As they entered the offices, Chief Executive Officer Xu Li was hoping to persuade the head of SoftBank Group Corp. to invest $200 million in his three-year-old startup.

A third of the way into the presentation, Son interrupted to say he wanted to put in $1 billion. A few minutes later, Son suggested $2 billion. Turning to the roomful of SoftBank managers, Son said this was the kind of AI company he'd been looking for. "Why are you only telling me about them now?" he asked, according to one person in the room.

In the end, SoftBank invested $1.2 billion, helping to transform SenseTime into the world's most valuable AI startup. The young company's valuation hit $7.5 billion this year.