TLDR of my "opinion" - they are popular because fiat is even dumber so they actually have decent economic merit by comparison, but they are still kinda dumb in that you don't need a blockchain at all and they are only used as regulatory arbitrage because regulators are bamboozled by the innovation theatre.
gave this same answer below but worth pointing you to this: https://njump.me/naddr1qvzqqqr4gupzpqnwn7y4hqdtgxj9ygngkfy7drgze2qkpr002c4yj08wxhlut36eqqxnzde5xs6rjv3kxcer2vp3lc8ac9
TLDR of my "opinion" - they are popular because fiat is even dumber so they actually have decent economic merit by comparison, but they are still kinda dumb in that you don't need a blockchain at all and they are only used as regulatory arbitrage because regulators are bamboozled by the innovation theatre.