Perhaps it is unfair to call those individuals "evil" per se. I would argue that the trauma that they carry with them is evil. Like a parasite that transmits itself through hurtful actions.

The only ways we can really purge this evil from society is either by removing the individuals from society, via prisons or mental institutions, OR by helping the affected individuals deal with the trauma that they carry. Break the cycle of evil, if that makes sense.

It's not black and white, evil and good here. This is a young boy who is acting out because of tremendous stressors.

This is clearly a mental health issue, and if the way you see it is reflective of how society approaches the issue, then this young boy is fucked.