Why do you think that's its primary purpose? It has lots of uses. The point is that it's doing fine, it hasn't "gone away." And if you need a non-volatile cryptocurrency for some purpose there are a variety of stablecoins designed to meet that need.
AI can't reach its promised capability of doing everything for us automatically
Your criterion for a "bubble popping" is that the technology doesn't grow to completely dominate the world and do everything that anyone has ever imagined it could do? That's a pretty extreme bar to hold it to, I don't know of any technology that's passed it.
It's just advanced Clippy and autocomplete. It can't replace anyone senior.
So it can replace people lower than "senior?" That's still quite revolutionary.
When spreadsheet and word processing programs became commonplace whole classes of jobs ceased to exist. Low-level accountants, secretarial pools, and so forth. Those jobs never came back because the spreadsheet and word processing programs are still working fine in that role to this day. AI's going to do the same to another swath of jobs. Dismissing it as "just advanced Clippy" isn't going to stop it from taking those jobs, it's only going to make the people who were replaced by it feel a little worse about what they previously did for a living.