At this point I don't know how easy it will be to ban it. Billions of dollars of institutional money have poured into it. As such, they aren't going to take kindly to government regulators trying to kill their massive investments. The best time to try to kill off crypto was BEFORE it became a mainstream idea. It is way too late for that now. Any country that tries to kill crypto will only make themselves look backwards in the eyes of investors.
Nobody needs to 'ban' BTC.
BTC will be de facto useless if market mechanisms correct for speculation. If falling demand for BTC causes price to drop below a level that makes mining and transactions lucrative, then BTC will no longer be a viable asset. It's already inefficient compared to newer cryptocurrencies.