Had two players like this before.
In case A, the player did not have a hobby named RPG. As a matter of fact, RPG was his raison d'être. He did not give a rat's behind for anything, as long as he could play one of his glourious and overpowered characters. Since he devoted his life for all his characters and for RPG, he was unemployed and was not the least interested in having a job or living a regular life.
It took us some time to realize that he was a walking bag of lies and stole from his friends - in this case, our money and property.
Case B was pretty easygoing in relation to the first example. It was a gamer who reacted like Monk described, and he spoiled many evenings by reacting emotionally to stuff he found unfair. Mind you, it was unfair, if his character lost some gear, for example, but it was funny as heck if another player's character lost something. Fortunately, this player left us after a while, because he was convinced the gamemaster was always picking on him.
The lesson I learned is to avoid players that care way too much for their characters. Perhaps they are not as bad as the first example, but they are definitely problematic. And since our time on planet earth is extremely finite, I guess we should avoid timewasters (in this case people whose presence and participation make our hobby unpleasant, so the time spent is wasted) and partypoopers.
If I was desperately in need of a gaming group, I would accept some minor emotional abuse, but I would not have my free time spoiled - or recommend it.