Understood. You are right, I really hate this...What happens to me once: man creates a character, Ive adapted the stroyline to be mutually influenced with his bio, we were sculpting this for some hours before the game starts...and then after two runs, he is kicked from his job and has time to read the rules there and back again, play with chargen. Then he came with something I call Exploit, character that was methematicaly perfect, but lacks any pieces of soul, and told me, thaat he dont want to play that character no.1 any more, but he wants to play this. Ive asked him why, argumenting that his character would develop with karma and if he dont like something right now, he may be able to change it in the future.
Then I saw 30 years old man behaving like a pure "egoistic child" archetyp:
NONONO I WANT THIS RIGHT HERE RIGHT NOW.
I`ve let him finish his tea and then kicked him out of the doors, telling him to GTFO of my sight. Well, good way to get rid of a friend. But we slowly realized, that the way he was always trying to stay in the spotlight, he was blocking other players and their ideas, and that our runs are much more joy without him.