I don't see how it can be a bubble (or at least a risky one) without much debt. Places like Google and Meta profit $100B a year from operations and are funding most of this from cashflow. The risk is that they have to write down a bunch of overbuilt data center assets in a few years, but lenders won't be going under because there aren't any lenders involved. And without lenders being at risk, the system isn't at risk.

*There is some leverage. Coreweave has borrowed a bit for example. But none of this is really systemic and no one is levered to the eyeballs in the AI space.