First: all stock exchanges must be banned. While this is very difficult. Exchange a lot. They are scattered all over the world. There, where one exchange disappears, three or four new ones appear. Exchange, as well as crypto-currencies, open up on increasing. Certainly not all of them will live to old age. But the fact that there are many of them is a fact.

Second: you need to ban people. Suppose you destroyed the stock exchanges. But here a different problem emerges. People can act without exchanges, they can exchange goods directly: Fiat for bitkoyn, bitkoyn for fiat, goods for bitkoyn, etc. It is impossible to control 8 billion people.

Third: the elimination of the Internet. This measure may also prove ineffective. First of all, a lot of people will protest. Secondly, the Internet can be made extra-state or independent of decisions from above. Thirdly, even if the Internet is liquidated, it is not a fact that you are eliminating cryptonyms. Cryptography does not need to have Internet access. People can create Bitcoin 2.0 out of the Internet.

Fourth: buying all the crypto currency. Also it will not work, because it is known that even one bitkoyna suffices for the functioning of the world housekeeper. Let them buy it. It still does not work. Bitcoin is not gold. It can not just be taken and taken away, or braked at the border.

Fifth: counterfeit bitcoins through the liquidation of miners. This option is possible, if someone has the power of the network in their hands. Since the network is decentralized, it will be very difficult to find all the miners. But this, in my opinion, is the most realistic option, because the miners become larger and now they are easier to find. But even if you eliminate all the miners, this will not solve the problem. The discoverers can simply release another bitcoin. Well, you banned digital "gold", and what has changed? People switched to digital "silver"