We all know that bitcoin/crypto being used for criminal activities is only minuscule. Countries just ban Bitcoin because they know they can't control it; simple as that.
As far as criminal activities are concerned countries percieve the impact of crypto to be rather significant. So even if 1% of crypto transactions are related to criminal activities, but 40% of all relevant criminal activities are handled in crypto, it is still a problem. I will not take a stand on wether banning crypto is effective in alleviating that or not, but it can certanly score some political points to be tough on crime and therefore be tough on crypto as well. So yeah, some calculations in banning crypto are related to criminal activities. Though it is certanly not the sole or even the most important consideration