It's not that easy to hide from the Chinese government unless you are skillful to hide your activities from the government agents. I think it will not be profitable because the general masses won't take such risks just for investing in bitcoins. They might face some big trouble if they get caught. If they will just let them trade with decentralized exchanges without any problem, then it would be good for them but if they need to hide just to trade, then that would be a high risk to take.