how they can banned it? they can not banned it. Who is accountable for bitcoin? they can not do it because btc is decentralized and owned by the public. If they want to banned it. They need to stop the internet and electricity forever.
They can stop exchanges from operating , banks from servicing accounts , preventing merchants from accepting coins and rounding up people who deal with bitcoins.
Those who act high and mighty behind a keyboard should read the story of BurtW
https://bitcointalk.org/index.php?topic=934268.0Many of those who stay the government can't stop it would have pissed their pants if they were in his place.
And many countries have darker and deeper cells than the US.