The most defining trait of Sociopaths and Psychopaths is having no empathy, so for people like this the suffering of others, be it of their own making or not, has about as much emotional impact as the "suffering" of a leaf of lettuce when they eat it or of a piece of paper they crumple and thrown in the trashcan.

This also means that, amongst other things, they feel no guilt whatsoever (would you feel guilt from eating a leaf of lettuce?!) and will sleep like babies with the blood of thousands on their hands.