Cognitive distortions and maladaptive behaviours can be pretty powerful. A lot of people that do harm don't believe they're doing so or have warped perceptions that justify their actions.

If you look at the rates of mental illness and mental disability in prisons it's clear that a lot of people do bad things because they were in a bad place themselves.

The amount of people that go through the Justice system (or preferably justice diversions or restorative justice considering the harm prison causes), are remoseful and turn their lives around I think is a testament to the fact that people don't want to do wrong or harm but do sometimes need help to do the right thing.