Consider what happens when someone buys your account. It’s not much different than someone who hacks into your account, and you don’t realize it. You’ve spent months, and maybe years building your account and lots of people on the board have seen your account. Perhaps they even know who you are. The new account holder happens to be a shyster who’s operating a business to steal people’s money through Bitcoin. Your once legitimate account where all of your friends kept in touch with you is now being used to tout an illegal operation as legitimate. Your friends think the account is still yours, and they send you a private message, but instead of it being you who receives the messages, the shyster receives them and replies with rhetoric. He’s able to convince your friends to use his service and steals their money, and your friends now despise you as they think you stole their money.