The real question is "how much would it cost me to solve a similarly hard problem?" which is impossible to answer without them giving the detail on how many of these projects they are running and how many tokens they are burning, something they don't tell us.
I tend to think of the market kind of like a social media feed, i.e. engagement matters. Even if they're establishing these results at an overhead, they're doing so with money that otherwise would probably never be spent on these problems, or would only be over very long timeframes.
Whether this is sustainable is where what you describe comes in. And it may not be, but that doesn't mean it isn't impressive. Lots of cool technologies in history that failed to justify their stay.
You are right that there is nothing wrong with, e.g: Red Bull sponsoring an extreme athlete to do some crazy sport that was otherwise never going to get funding. It's true that otherwise they were never going to get funding for it, but it's advertising for Red Bull and something cool for people doing something interesting, win-win.
I think the difference is that Red Bull have a very strong income stream that funds it. Currently all these AI companies are burning investor money, and to me, that looks less like "savvy advertising" and more like "pumping the bubble".
[1] https://www.businessinsider.com/openais-math-dump-rattles-ma...
Or consider the algorithmic complexity classes underpinning all of this, not just P vs NP, but also whether quantum computers are actually a distinct class, since that is not proven yet either afaik. The reason we're moving to quantum resistant algos in the first place.
Remember when OpenAI published 700 math break throughs and absolutely none involved cryptography?