The goverment from many country is worry whe the money in his teritory is going in other country who can his country in bad condition and its can makr a crisis
The reason why cryptocurrencies ban. because other country doesn't know what cryptocurrencies means.. They not know what is this that's why they ban.
I think they know only from the negative side and determine the policy only from the bad side. bitcoin poses a threat to local currencies so many countries forbid it. that is from the negative side. of course there are positive aspects such as financial benefits for many people and so on