i think bitcoin is not gonna ruin a country but bitcoin will help the economy of a country with giving more benefits to citizen when they use bitcoin in daily life but this is not yet realize by government or they know before. its like using fiat in a country but we have more benefits that we can use it in many places in other country.
if a country uses total bitcoin as their currency, there will be two results that will occur one about the excess or a plus for that country, namely the community will benefit, especially business people in that country they are very easy to buy and sell, tourists will also very easy, because travelers no longer need to exchange their money into the country, but there are losses that will occur, bitcoin does not have a feature of credit and collateral to finance one of the goods, there is no credit, the business people will be very difficulty in financing their businesses which are usually borne through credit.