Psychopaths are people thatw know what's good for them but simply don't care about anyone but themselves.

Most criminals eventually pull out the remorse card or try to justify that their behavior is right, or lie about the real motive for their violent behavior.

Most of these criminals despite their serious mental issues, they can still function and lead a perfectly normal life.

For example they are able to work, have friends and socialize.

And they have somebody in their live they love more than anything.
It's other people they care nothing about nor would feel any pain in destroying them.