I imagine there are numerous reasons people on player-versus-player (PVP) game servers battle one another, both surreptitiously and through subterfuge, and overtly with apparent declarations - the variety of which also accounts for my own presence there, despite never being the aggressor. I employ a pay-it-forward outlook, assisting and helping others where I can, never interfering with another's quest. There are those who believe however, that presence alone on a PVP server is a license to asshole. So be it.
These types generally generate a pervasive noise on chat, ceaselessly extolling their own virtues, all the while bullying other players. I never interact with their drama unless I myself am killed, and even then, I do so silently.
The odd thing about these individuals is their uncanny ignorance of game-mechanics; the same game they're currently playing. My low-level character is rarely the only character on the server. There's nothing quite like signing off after I've been killed, logging back in as my level 60 reaper, hunting them down, killing them in the midst of their show-off, then logging in again as my lowbie continuing to play as if uninterrupted. Watching their varied and punctuated reactions is always amusing. As is ignoring their verbose taunts and immature name calling.
I love being an adult.