Cory Doctorow made a very specific point about this on This Week in Tech 1074, in the context of comparing the growth of the Internet with the current AI market:

The web lost money for a long time. And it’s true, they did, but they had good unit economics, right? Every user of the web made the web less unprofitable. Every use of the web made the web less unprofitable. And every generation of the web made the web more profitable. Contrast this with AI, where every time they sign up a user, they lose more money. Every time the user uses their account, they lose even more money.

And every generation of AI accelerates the rate at which they are losing money.

I think it sums up how unsustainable this is very nicely.

it’s okay, somehow i’m sure the american taxpayer will bail them out