Urgh. I hate it when I post something and accidently forget to change the username. Now I'm stuck with this stupid name for the whole thread.
Anyway, bullies bully because they enjoy it. I can still see the faces of my bullies in my head. All of them, and there were many, have smiles on their faces, they are having a good time, what they are doing is fun to them, it makes them happy.
Even at the time, as a pre-teen and teenager, I remember thinking, as they jeered at me and hurt me physically, how happy they all looked. Sharing in this happy, fun group activity. I bet some of them sit and remember it fondly or laugh about it still with each other.
You can come up with all the reasons why they do it that you like, but it does all boil down to - "because they enjoy it".
Even the ones that "had a shit home life" ultimately do it because they enjoy it. They are angry and they are hurt themselves, sure, but they still enjoy having an outlet to those feelings.
So if you started this thread to get answers for how people treated you (I don't know if you did, but if you did) then there is your answer - they liked it, they thought it was great. That's why they did it.
And I actually found comfort in that, because I could finally understand that it wasn't because of me, they weren't doing it to punish me because I was bad and deserved it, they weren't doing it because I needed to be taught some sort of lesson because there was something wrong with me. It was nothing to do with me. They did it because they liked hurting people and I was a person they could hurt. Simple as that.
I genuinely hope that's answers your question.