Not an asset class, but I'd draw parallels to Texas Hold 'Em. In 2003, Chris Moneymaker wins $2.5 million at the WSOP as an amateur who qualified through the internet; within a year, everyone is talking about hold 'em, their bankroll strategy, having poker nights with their buddies, how they're playing 12 tables at once online, etc. Culminates in massive mainstream acceptance, ads for Pokerstars running on major networks, and a major plot arc in a James Bond movie. But it turns out that nearly everyone is a loser in online poker; after all, at a 6 person table, only 1 person wins (well, 2nd place usually gets their entry fee back, but still). Very few people become Chris Moneymakers; most just lose a bit of cash, some their life savings.

Look at where hold 'em is now. It still exists, of course, but you don't see poker tournaments broadcast live on ESPN anymore. It's not even a very popular livestreaming category. It definitely went through a boom, then huge bust, and then a slide into... not really irrelevancy, just kind of a continued existence.

IMO, crypto is headed for the same fate. It will still be fun for a subset of people to gamble on altcoins, to pump and dump and run schemes of dubious legality. And just like I wouldn't count out a poker resurgence sometime in the next decade, I wouldn't count out another crypto spike in the future. People never stop loving easy money.