Masayoshi Son, boss of SoftBank, a Japanese tech and telecoms giant, is one of the boldest investors of modern times. He earned billions from prescient investments in Arm Holdings, a chip company, and Yahoo and Alibaba, two internet pioneers. Yet Mr Son also vaporised billions with astonishing speed by staking the likes of WeWork and countless other tech confections. Revered for his insight, he is mocked for his overreach.