Lot of countries do not allow to use crypto currencies and they discourage using them. However as far as I feel, trading with crypto is not that harmful for the economy of the country. As an example, if a person has Eth and someone from another country needs to buy Eth, that buyer needs to pay the seller in terms of dollars. Then that seller needs to convert that Dollars to his native currency which means it creates a the demand for the native currency and increase the value of the currency. May be the government is unable to add a tax on such transactions but it is beneficial for the currency used in seller's country.
What do you think about that?
Banning crypto is the worst thing that can ever be done by the governments - they close the opportunity for their population to earn some decent money and improve their financial situation.
In its turn this prevents the increase of purchasing power and the subsequent revival of the economy. This especially concerns underdeveloped countries, where crypto could become a remedy to many problems.