In a simple image the reality is well explained. It isn't an easy think as the governments think. Maybe in the early days if they have planned to stop its usage, the governments might've got an opportunity. Now scenario is different and people are well aware of the need and they keep on making loopholes even if something is done outright to stop its usage.
Can government completely ban Bitcoin or not? To find answer to this question one must consult Bitcoin Whitepaper, on very first line we find this:
"
A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution."
Bitcoin WhitepaperBitcoin was designed from scratch to overcome limitations of existing financial system, where every transaction has to go through a central authority for approval. Since there is no central authority in Bitcoin then how can it be banned ? Go through Bitcoin whitepaper and we can find answer that why governments are againest it and why it cant be banned.