OpenAI/Anthropic's purchase obligations don't matter. They are made to companies with plenty of cash, real assets, and other revenue streams. The only thing that happens is that AMZN, MSFT, GOOG squeeze out some upstart rivals and stay on top.
All of the compute being built will be consumed very profitably, that profit just won't be captured by delusional weirdos who believe they can build an AI god because machine elves showed them the future in a DMT trip at a poly sexy orgy, or whatever the case may be.
No doubt, but a lot of investors believed the delusional weirdos and so have invested as if every human would be replaced by a sentient AI.