Well sort of both, but many of us use exclusively as currency. For instance, I generally only hold it long enough to make some bitpay transactions to avoid CC fees.
2. Reversible transactions for fiat currencies is a feature not a bug;
Feature of some fiat transactions, but you can avoid that with fiat too. Some people WANT irreversibility, but you're free to use fiat instead if you like.
3. People who can't manage passwords won't be able to manage a wallet so mass appeal is always going to be limited;
OK fine, they needn't use crypto.
4. Crypto has its own vulnerabilities (eg 51% attack);
If 51% militantly attack the treasury and fed it won't exist either.
5. This whole system is hugely energy wasteful; and (here's the big one)
Your beef is with externalities of electricity. I don't like that either. Lets fix that rather than play whack-a-mole with whatever use of electricity you disapprove of.
6. Government action could shut down crypto tomorrow so how robust is it really?
All I can say is good luck with that.