Government cannot make the btc illegal worldwide because bitcoin is not linked or controlled by any financial institution.  The blockchain doesn't require any agency to operate it.  If the government will require to stop this, they cannot regulate the entire network.  Even the true identity of the wallet owner, it is very difficult to find the real person beyond a wallet.  They can also hide their identity by moving their wallet into offline form. If the government wants to stop it, it is very impossible for the government as of now to control anything that is digital