Why are people evil on purpose

I’ve never fully understood the idea of people being evil and conniving on purpose. I kind of get some of it, I have homicidal and rude thoughts and I am a bitch, but I never like it to get farther than insulting slow walkers in the halls and being more harsh with my language… aside from that I try to be as reliable and understanding as I can be. 

I don’t understand how people can go father. How can you put a knife to someone and feel okay with it? I was learning about Hitler’s rise to power and I thought the idea of it was really weird. What was the point? Why was he so threatening and evil? 

I have four reasons for hurting people, all of them caused by neurodivergence. Either, I say something that’s meant to be only very slightly rude but ends up being really bad and I don’t realise; I might simply not understand the other person’s emotions and therefore not care for it, like it’s invisible because it kind of is to me; I genuinely think I’m correct in a situation and act as who I believe myself to be. Sometimes I genuinely just don’t care and say hurtful things but that’s almost exclusively towards my father. I don’t act like a manipulative little dickhead because I’m actually trying to be like that I act like a manipulative little dickhead because I used to have the emotional intelligence and empathy levels of a pebble. Nowadays I’m a little better with it and I can understand people more so I don’t hurt them but I do still make mistakes and insult people without fully meaning it.

So, as someone who’s fought to NOT be like this, I don’t know why people do it on purpose. I don’t know why people manipulate/groom others for harmful reasons (manipulating is fine if it’s for good imo). I don’t know why people actually do all of this on PURPOSE. I probably look like such a cunt because people compare me to these people. I swear on my cat I’m not mean af on purpose most of the time. do they know they’re being evil? Do they just not care? When I was being a toxic person I thought I was right and I stopped when I realised I wasn’t, because I wasn’t doing it to be evil I did it because I thought I was a victim. Is this not how everyone works. are some people jusr evil for fun.