Why are their so many a**holes on WoW?

So I recently began playing wow and alot of people are really mean. I still don't quite understand gear and the stats. So I had one piece of agility on my mage (now I know only intellect) but someone on my server told me "You F***ing suck go sell your account you nooby F*g" and many others say horrible things, even in radom dungeon finder :( I'm new at the game so I'm not quite experienced why do higher level players treat low lvl's or noobs like crap :/