I...actually agree with Charon. People enjoy the game in different ways, and for some that involves smashing faces and gloating about it. I dunno if it's really fair to go Armchair Psychologist on them and start claiming it's because their life has no meaning and their parents never loved them, (or some of the other accusations that float around towards WAAC players.)
Speaking as a casual-as-heck gamer who just uses 40K as a reason to get a chat and some time with mates, and have a bit of a laugh.
People of different clans are going to be abrasive towards each other, though. You see it online with the eternal Warmachine vs 40K arguments that go nowhere, and people approach 40K from different directions for different reasons. Is it a symptom of a complacent, sedentary society? No more so than anything else, really.