I've met quite a few comp players, and it seems like the TRUE professionals are usually not douches, but the lower tiers of comp players have a serious case of unwarranted self importance.
Basically the same as people on console that feel like the master race because they play gamebattles. It doesn't matter if they lose, they play comp so they are better than you by default!
That annoys me. People who probably get destroyed on tf2lobby that act like every match is some sort of ESEA-I match and makes excuses for every damn death or loss they get in a pub, and is very often seen with a personal buttmedic that refuses to heal anyone else because they're scrubz!!!
It's kind of ironic to see someone go all "lolol u pub scrubz r so bad stop playing" while struggling to stay afloat in that very same pub