The DotCom bubble is an instructive historical example. Pretty much every wild promise made during the bubble has manifested, right down to delivering pet food. It's just that for the bubble to have been worthwhile, we would essentially have had the internet of 2015 or 2020 delivered in 2001.
(And because people forget, it is not too far off to say that would be like trying to deliver the internet of 2020 on machines with specs comparable to a Nintendo Wii. I'm trying to pick a game console as a sort of touchpoint, and there probably isn't a perfect comparison, but based on the machines I had in 2000 the specs are roughly inline with a Wii, at least by the numbers. Though the Wii would have murdered my 2000-era laptop on graphics.)
I don't know that the AI bubble will have a similar 20-year lag, but I also think it's out over its skis. What we have now is both extremely impressive, but also not justifying the valuations being poured into it in the here & now. There's no contradiction there. In fact if you look at history there's been all sorts of similar cases of promising technologies being grotesquely over-invested in, even though they were transformative and amazing. If you want to go back further in history, the railroad bubble also has some similarities to the Dot Com bubble. It's not that railroad wasn't in fact a completely transformative technology, it's just that the random hodgepodge of a hundred companies slapping random sizes and shapes of track in half-random places wasn't worth the valuations they were given. The promise took decades longer to manifest.