I'm wondering this because is such a real threat to bank system and we all know how banks and governments are tightly linked !
BTC could make people more autonomous, self-resilient, being their own bank. You can use it like cash, making your transaction almost untraceable (or untraceable using e.g. monero or dash or laundry systems) : this is governments worst nightmare, isn't it ?
Governments do not want to legalize Bitcoin because it causes the government to lose control over the deal. They worry about the security and the illegal money can cause severe consequences. The other part is like your opinion. Governments and banks cooperate very well. Bitcoin again threatened the bank.