Destroyed in what sense? Some people have already said that if or when governments 'ban' cryptocurrencies then bitcoin will die but in reality is it even possible to ban bitcoin. The fact that is it decentralised and controlled by nobody surely protects it from this. Banks for sure could ban clients using their cards to buy bitcoin but in the long run i dont see this lasting as it just takes one bank to accept its clients to buy bitcoin to change the ideas of the others as this bank would surely become very succesful and profitable!