Then everybody will wonder why and want to use them. The ban would not work anyway and it will make the government look really bad. There is a country in South America that has banned it but I dont remember which onw.
Not really instead it is the other way around. Remember Governement have all the power and trust of the majority of its people. So if the government labeled BTC as illegal and banned it, those who are holding BTC and trasacting with it will really look bad. Because these people will go underground transaction in order to use their BTC.