I strongly agree that banning cryptocurrency is no longer possible. It is now big part of digital economy used by millions worldwide. Cryptocurrency is hard to control because it us decentralized and transactions are anonymous. Banning it would be impractical and could harm economies.
Bitcoin is accepted for online shopping in many countries showing its growing popularity. Even in countries where it is not allowed people still use it secretly. And my country is one of them.
I will also agree with you that banning cryptocurrency in any democratic country is definitely not possible. Because it has created a decentralized economic system that works peer to peer and that's why the government can't crack down crypto at will. Moreover, a cryptocurrency is not limited to only one country, it is connected to the places in the world where there is internet.
In this case, it can be said that in the countries where dictatorship is going on, people can be temporarily stopped from using cryptocurrency by shutting down the Internet, but in the future, they will have to open the Internet and for this reason, it is not possible to crackdown on cryptocurrency.