Linux

Why are so many linux advocates obnoxious as fuck? I have nothing against linux / open soutce software, but it seems like if you ever make any criticism of their OS they tend to go all "M$ fanboy" at you, or make ridiculous ad hominem attacks when they get riled up.

Why? If you are a linux fag, why do you do this? If you don't do this and are a linux fag, why do you think others do it?