They survive through inertia and “new model novelty”.

The minute they lose that (not just them, the whole sector), they’re toast.

I suspect they know this too, hence Sam-Altman admitting it’s a bubble so that he can try to ride it down without blowing up.

This makes sense, but what happens when they stop burning cash on training runs and any of their competitors releases a better model that raises the ceiling?

They will have to train one that is comparable (or better), or the word will spread and users will move to the better model.