The difference is once you bought one of those chips you could do your own innovation on top of it (i.e., with software) without further interference from those well-funded companies. You can't do that with GPT et al. because of the subscription model.
You can do some, but many of them have license restrictions that prevent you from using them in certain ways. I can buy an Intel chip and deliberately use it to do things that hurt Intel's business (e.g., start a competing company). The big AI companies are trying very hard to make that kind of thing impossible by imposing constraints on the allowed uses of their models.
