Replying to Skaters vs. BMX

So i rollerblade, but today i was at a skatepark and this one skater was really picking a fight with a BMXer and he hit him with his deck and hes was bleeding like shit and it made a big puddle o'blood in the park. That's nasty. So then the skater, witch would of goten his ass kicked by the BMXer (witch was pretty beefy), left and the police came and the guy left in an ambulance. The fight started just because one guy stepped on the other ones skateboard. So all that to say: why so much hate?