You are not disproving but rather reinforcing my point. Amazon survived the dotcom bubble precisely because they could hope to do more than deliver physical books. It was a more flexible, generally applicable business model than pets.com, and they started out targeting a market more susceptible to ecommerce conversion than pet food delivery proved to be. Similarly, a company selling a product that can only be used for the limited use cases we have found for chatbot-style text generating LLMs will be more likely to fail than a company selling something that is more generally useful. Data centers are more generally useful than LLMs, and the companies building them are more likely to survive than those whose fortunes are pinned entirely to unrealistically high expectations for replacing white collar workers with LLMs.
Data centers aren't just physical buildings though - the vast bulk of data centre costs is the racks of servers in them, and those are being bought and installed on credit at very high costs.
Its not about "is a computer thoeretically useful" its about if it's going to deliver value to cover the cost of installing it in the first place over it's expected lifetime.
You aren't substituting generic compute: you're substituting highly optimized GPU dense server space. The application is more limited then it looks.