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 ?
It is not that every government intends to ban or deem cryptocurrency activities illegal, but I think it just comes from the duty of a government to protects its people. A government, being the leader of its country, has the duty to protect its people including againt bad business. The cryptocurrency market, having a negative image, always puts the government in its toes to try to help people not experience anything negative due to the effects of such market.
The governments intend to have control over how things are run, so they jump at any opportunity. Its how they run, giving them access to a decentralized network would allow them to have power and power means control over its people, in terms of what to buy, what to invest and what not. Making BTC illegal worldwide would be a bad move, equally banning it in some countries creates competition with the other ones which legalize BTC. It's just one of those difficult decisions.
