alt Hacker NewsFinite doesn't mean small. We have no idea how much they are burning in the back to do this. If you are taking things people just don't care about enough to invest the necessary effort/money to solve, and spend way more than anyone else is willing to spend to solve them, the solution could be less AI and more access to lots of investor money you can burn on PR.
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 have considered this angle before, but landed on that it's not like anyone was ever actually going to do so.
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.