From visionary bets in Yahoo, Alibaba, and Arm, to disastrous gambles on WeWork and Vision Funds, SoftBank's Masayoshi Son has defied both logic and expectations.

Self-styled as a modern Genghis Khan, the once richest man in the world has rolled the dice yet again, plowing money into OpenAI and Stargate. 

'Masa' is set to put in at least $19 billion into the $500bn AI data center venture, as well as invest in OpenAI so it can fund its own $19bn contribution. He will serve as chairman of the company, while SoftBank will have financial responsibility over the entire endeavor.

What can we learn from his past gambles? How real are his promises? Is he a visionary or reckless trend chaser?

To understand the man behind Stargate, we talk to Lionel Barber, author of the new book Gambling Man: The Wild Ride of Japan’s Masayoshi Son.