I would say that the state can control the currency, but most likely it will use it to its advantage, here are some examples of the proper use of cryptocurrency:
1)Taxes are needed, but minimal. It is important - the first three years, for example, the ICO should be exempted from taxes. And then the country will receive: a) huge liquidity (one ICO - the budget of a region or even a few small ones); b) new funds on deposits; c) new business entities; d) a huge labor market; e) additional funds from related services (purchase of traffic, payment for the work of specialists).
2)Mining Divide it into industrial and home. For example, in terms of power: up to 15 kW - home, over - professional. I always cite the example of hosting: I do not pay any taxes for home hosting, I do not get licenses. Another thing, when it is put on a grand scale.
3)Training. Free and for all: this will remove the issue of investor professionalism, for which (allegedly) many officials are experiencing. Are you afraid that a person will invest in ICO and burn through? So teach him how not to do it: bans will not become a barrier - Forex has already proved this, and binary options have put an end.
4)No interference in the zone of complete virtuality: control only over the points of entry and exit. Why go where there is still no competence? Even Japan, and this country will certainly give two odds on manufacturability, has refused to regulate this aspect.
5)And the main thing is to stop looking at cryptocurrencies as something absurd: this is the future that has come. All that is needed is not to interfere with its development, otherwise we will lose again, as was the case with bank cards, the Internet, online services, PC development, etc.