Bubbles happen. But you hope what is left behind after the bubble supernova is at least useful to science or society. Like the dot.com bubble for example - we at least ended up with the web and internet/mobile innovations after all the dust cleared. There are other bubbles brewing with no clear end game as well such as fusion technology and self driving cars to mention a few but these as well will leave useful science behind as they cycle from winters and summers. Unfortunately with crypto, blockchain and web3 what will be left behind is only radioactive waste and greed.
Other than ransomware, war zones and failed states where have digital coins been used for commerce? And no, saying “but blockchain is awesome” doesn’t fly either. Ask the same question about the technological mythical Satoshi Nakamoto blockchain marvel. Decentralization is great in theory to free us of the shackles of centralized control - but rule by the mob and the digital immutable consensus powered blockchain ledger of decentralized servers and exchanges (btw still ruled by a few) is not going to lead to a happy ending.