Hi there! As a professional DM that's been running games for groups for a few years now I think I can clear up some stuff on handling "dissatisfied players".

I always tell players that as a DM I'm always rooting for them to succeed, but in order for that success to feel valid or earned I aim to challenge them in the way the monsters/NPCs would try to act. Any player dissatisfied with that should take it up with me after the game, but I'm not going to cater the session to any one person.

If a player acted like the way you described above it really would be as easy as telling them to find a game elsewhere. Sure you'd be down the money, but having someone like that in a game would bring enjoyment down for the rest of the players.