Why are some people just good at making fun of others?

Like my friends always keeps roasting me or backbitch about others, I don't get how they get up with funny jokes. They do not joke harmless, they joke like they are insulting others. After being tired of me getting insulted all the time, I sometimes try to make them taste their own medicine but it's not just who I am. I can never truly enjoy making fun of others, it's not me. How do you deal with it?

Why do some people also don't realise or are they always aware but they do so because it's fun to them and they have this thing in mind that friends are meant to make fun of each other and just roast all the time.

I'm so sorry it feels like a vent. It's actually both vent and I need advice too.