When a country bans crypto, black markets for it inevitably pop up. The opportunity for profit is just too good to pass on when you could become one of the few players in the country offering crypto brokerage for the public.
These tend to disappear the more accessible crypto becomes in that country via legal services, however.
There will always be opportunities like you said wherever they are implemented, because these opportunities can be, done and cannot be avoided through mechanisms that might be implemented, because of their ability to do so without permission.
But as good citizens, it is not appropriate for us to violate the rules that have been made because it will always be risky, and it is not a good thing to do, even if we can.
However, currently more and more countries are able to provide convenience even though they do not recognize but are allowed to trade, thus avoiding the intention of violating the rules.