If crypto does gain massive adoption and you are able to pay for things in crypto, there would be less of a reason for people to cash out into fiat. How would government collect taxes from crypto gains then? Also, if something like ETH becomes big, how is the government gonna stop people from making pyramids, ponzis, and scams in general?
I guess the dream of everyone already into crypto stuffs for them to be able to use crypto like the way they will spend their pounds, dollars, yuan, etc. But in practice, there are no such markets yet, or maybe just a few in some selected regions.
Adoption is still an ongoing process. Nobody said we're ready for mass adoption yet. The points you raised are all valid and there are still a lot to be done on crypto for it to be more usable.