If government ban the use of btc or other form of cryptocurrency, it will still continue to be existing and trading because btc is decentralized in nature and not easy to control by any body.
In a government policy, a country can ban bitcoin from being used in its country, but in practice the government cannot supervise all its citizens so that it does not trade or invest in bitcoin. Internet users cannot be monitored, if in their country they have problems, they can use proxies from other countries. While the results from bitcoin enter the e-wallet, continue to the payment gate and enter the local bank account. The government can't do anything because everything happens in cyberspace.