SoftBank Group sold its entire stake in Nvidia for US$5.83 billion to help bankroll artificial intelligence investments, even as investors question the amount of capital pouring into a technology with uncertain returns.Founder Masayoshi Son has been unwinding positions to pay for a plethora of AI projects, from Stargate data centres with OpenAI and Oracle to robot manufacturing sites in the US.The Nvidia exit coincides with a growing debate about whether spending by Big Tech firms like Meta...