bad upbringing, Tormented themselves when they were younger etc (which in no way excuses their behaviour )

mess don't let this flop this is a good topic.

A strong id and a weak superego.

+1 , with a mix of entitlement

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Nothing excuses their behavior, but it does explain it.

I do it for fun. Not sure about other people though!

Lack of empathy is my go to.

If they have a high capacity of empathy and they still commit anti-social acts, it's usually because they have an even higher capacity of (blank) that overrides their ability to be empathetic. Our minds are just projections of the underlying biological framework. Some people just have a higher capacity for anger/sadness/disgust/schadenfreude, whether that's for genetic reasons or because of social conditioning, or both (which is more likely)

Also, rationalization is a dangerous tool at times. People will go to the grave saying they are against sexism/racism/homophobia whatever, but as soon as some white woman calls some black guy the n-word, people will throw bitch/c-word/body-shame etc her way and justify that she deserves it, so it's ok if they are being misogynstic/sexist. It's very easy to fall into that pattern and a LOT of people do it. Killing/raping/abusing is just a few steps up from language with the exact same pattern. They deserved it, my actions are justified.

edit- not to say that the n-word is of the same gravity as a word like bitch, cause no one wants to play that game. But the gravity of a statement isn't the point. The point is the willingness to put something negative out into the world

- mental illness
- severe abuse and/or neglect
- drugs

it's normally one of or a combination of the three

Look superego up, michael is correct.