think the ban on crypto-currency in some countries is mostly due to the fact that the state can not regulate the crypto-currency market, the inability to tax income from crypto-currencies, because the state can not track transactions with the population. I think with time the situation will change
if there is no supervision and only prepare rules for taxes and what is permitted / not done, then the situation will not be controlled, at a minimum they must get the full role of the local exchange market or actually control total income through taxes, if this is left, then inflation can happen at any time.