AI chipmaker Nvidia beat Wall Street expectations this week, announcing soaring revenues while downplaying growing fears of an AI bubble. The company’s chips have been at the center of the ongoing AI boom, with AI companies’ valuations soaring to astronomical levels while their revenues continue to lag far behind. “You’re investing in something that is a perishable good,” economist and author David McWilliams told Fortune, calling AI hardware “digital lettuce” that’s “going to go off now.”Worse yet, GPUs could also become obsolete as the technology improves. McWilliams isn’t the first to point out some eyebrow-raising accounting in the sector. More on the AI bubble: Nvidia Gloats as It Defies AI Bubble With Massive Revenue