there is no rules that says people can't sell his PoB at anytime he likes

Don't take POB for much granted. If everyone started thinking like this then there will be huge line of sellers and limited buyers. Even selling 100 POB will literally take months, will you guys like that. Just look at many dead other Tokens on Hive Engine, you will realise what I am trying to say. There are plenty of tokens on Hive Engine having 24 hours volume to 0$. Go ahead and keep selling your POBs but literally don't cry when there is no one to buy. But Offcourse people will always do whatever they "like". Peace ✌️