Ive played just about everything (PC wise) for about all genres. MMOs (be they RPG, FPS, etc), I tend toward solo play (at first), then i progressed to PvP (the @$$holes ViperaAspis mentioned were quite prevalent, but fairly easy to ignore once you get into the rhythm of things). In the end, Id say that even though we can over-focus on games, we are still quite grounded in reality. Some NTs (and perhaps nons as well) let themselves get engulfed in the scenario so much, that temper's flare.
"WHY THE *&^% WERENT YOU DEFENDING"
my reply, "I didnt see you defending either, so what are you complaining about? Im here to play, winning is a bonus."
"ONLY A LOSER THINKS THAT WAY!"
"Says the guy trying to obtain something that has no corporeal value in the real world."
He shut up real fast after that.
Essentially, they get so caught up in the moment that they seem to lose all sense and get caught up in something that doesnt have any bearing in reality.
Now that was just a PvP example (Player vs Player). On the flip side is the PvE (Player vs Everything) which implies quests, and dungeons where you have to work with other people (often a random group) to clear the zone(s). These can actually be quite fun, especially if you are part of a guild, and the people in are are respectable and know what theyre doing. However, if you do the random thing (called pugging, for reasons im still trying to figure out), there is a markedly higher chance of getting a "Rage Gamer" as SkittlesMcBingBing puts it. These are the people who have devoted so much of their life to the game, that they cannot accept doing things any way other than their own, then flare at even the slightest display in difficulty. These guys are only in it for the gear (often ninja-ing drops from players who REALLY need it to move on). Bear in mind that these types of gamers are frowned on, and often reported by the players who, like us, want to enjoy the game. Believe it or not, the PvE ninjas arent as common as you think . . . but being in a guild reduces the chances of coming across one >.> As for the FPS crowd, theyre a complete loss seeing as how they act no better than sports fans (and i mean the over-zealous, "OUR TEAM KICKS YOUR TEAMS @$$" types). With those games, just turn off the teamspeak (unless you know the people well enough to hold an intelligible conversation with them) and do your thing . . . you know what to do, and dont need some hormone endowed teen know it all to tell say you suck when apparently he has yet to even learn self control. The good players will tell you what's up and potentially going to happen, the bad players tend to fling insults in hopes of compensating their lack of self esteem (and skill for that matter ).
So, buck up, take a deep breath, carry some extra ammo, a lot of wit, and some humble pie to serve the people that attempt to ruin your day . . .