What are the threats to the $1trn artificial-intelligence boom?

“The risk of under-investing is dramatically greater than the risk of over-investing,” said Sundar Pichai, the boss of Alphabet, on an earnings call last week. He, like lots of executives nowadays, was talking about artificial intelligence (AI). More specifically, he was talking about building more AI data centres to serve the customers of the tech giant’s cloud-computing arm. The sums involved are eye-popping. Alphabet’s capital spending is expected to grow by about half this year, to $48bn. Much of that will be spent on AI-related gear.