as you know, there's alot of players (if not most) that are addicted to WoW, they play 24/7/12/100 :P and i dont know how many times it happend but i know it has it was in the newspaper, a kid suicided because of WoW... he was 13, (chinese of course:P) anyways, the thing that really kills the player is...LAG :P nothing more :P
(the kid wrote in a letter" i suicided cause i wanna join the hero's of World of Warcraft")..... but i still think it's the lag >.>