The argument is based on one of these companies hitting the singularity, making it impossible for any other company to catch up ever. I still think it's way more likely we'll see a typical S-curve where innovation starts to plateau. But even a small chance of it happening in the future is worth a lot of money today.

That's certainly how it looks right now but where's the guarantee? What happens if it turns out that deep learning on its own can't achieve AGI but someone figures out a proprietary algorithm that can? That sort of thing. Metaphorically we're a bunch of tribesmen speculating about the future potential outcomes of the space race (ie the impacts, limits, and timeline of ASI).

They're months behind now and have very low market share, so as long as they stay months behind the duopoly/triopoly can hold.