there are main reasons the prohibitions against cryptocurrency. at least those factors are
1. the cryptocurrency mechanism is different from the current mechanism. it takes decentralized that categorized as a threat and doesn't any fit regulations to control those.
2. unknown parties have possible to do money laundering, so hard to detect with authorized financial regulations to track them. it broadens risk against the clean policy about fund resources belongs
3. there are not official regulations that control the fund within the market. it is impossible for them to make/search/intertwine mutual agreement that relates to policies or anything else. no one has take the responsibility.