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.
Yes. They can't benefit bitcoin since its out of their control, so might as well ban it. Countries' government would not only consider their people's interest but also their own and personal desires. If they can't earn big from it, then its better for bitcoin not to exit anymore. But not all countries have tried to ban bitcoin, some are still left undecided whether to accept it or not.