Government cannot ban bitcoins. If they were able to, then by now you would have been running here and there to the banks. The reason for which government cannot ban Bitcoins is that due to the decentralised nature of the coin. Due to this, no other person or organisation can know how many Bitcoins I am holding or have in my wallet. But yes they can ban or blocklist the exchanges for which we wont be able to cash out the Bitcoins through exchanges. But guess what! We have always P2P deals available in order to encounter this. Hope this helps you OP to understand the things better.
P2P made buying and selling of coins easier with good exchanges. Banning of Bitcoins is impossible because there are still other means Bitcoin operation can be carried out, it's users making transactions daily and it's massive, with the aides of exchanges. Bitcoin operation can be prohibited in some certain extents but can't be ban, the government can not ruled out the multitude choice but they can reduce it, looks like when the government tried even harder to put an end to it, that's the more privileged people are getting more educated on bitcoin and how it operates.