A government could totally ban crypto.

If I wanted to do so as a leader I would:

* Log which citizens visited any crypto related domains (exchanges, crypto wallet app servers etc.)

* Make a law banning the holding or exchange of crypto. Give everyone 1 week to comply.

* Make a government address to send coins to for disposal, and publish a form to fill in to say you have disposed of your holdings.

* Contact everyone in your log telling they need to fill in the form (even to declare they no longer have any holdings).

* After the deadline, arrest anyone who has not filled in the form or who declares zero holdings and subsequently visits exchanges etc.

* Sure, this method will miss some who carefully use tor. But that's a tiny minority. *