GUYS ONLY: can you tell me what is up with these dudes???!?

so theres this group of guys in our grade (sophmore) and they're SO. MEAN. theres like 6 of them, they're really popular though because they're super atheltic, they get 1st at like everything they do, and they're like the richest people in our town. they all have a lot of money, and they're all honestly like the best looking guys in our grade. i mean they're HOT. but theyre hideous because they're so mean. they ALWAYS pick on people, push them against the hallways, tell people everyday they're fat/ugly and should go home and kill themselves. they then say "just kidding damn CALLLLM DOWN." and the thing is they only pick on people when they're with someone else in their group. if they're alone in a class, they'll just sit in the corner and be mostly quiet. they'll make crude comments sometimes but not a lot. so whats up??? some ppl say they're insecure but i doubt it, they've got everything, theres nothing going on in their homelives (its a small town i know their families) and everythings set for them, and they're actually super cocky cuz they know theyre hot and good at everything. so why are they so mean to ppl when they're around each other?