Venture capitalists have a professional obligation to be optimistic, but David Cahn, a partner at the storied US fund Sequoia Capital, has spotted a $US500 billion ($763 billion) hole in the year’s biggest economic narrative: AI.

That figure is the gap between the AI revenue being generated each year – which Cahn puts at about $US75 billion – and the staggering sums businesses are investing in buying, operating and ultimately trying to profit from AI chips.