In fact the use of bitcoin is banned in some countries but I think selling bitcoin excluding illegal action because there is no legal binding that if you sell or buy a bitcoin will be in prison.
can you mention the names of the countries where bitcoin is banned? and if their users are using it they put them in prison? and the second is that do you know about any one happening when any government arrest a person for using bitcoin illegally? for me i think i never hear any official announcement that any country have banned the use of bitcoin. and never seen any person who has been charge by the government for using bitcoin.