Psycopaths are functional, the thing with them is they don't feel empathy, not that they like killing, no empathy equals not givimg a fuck about anyone you kill.
I don't feel empathy for the bums I see lying in the gutter, but that doesn't make me a psychopath, does it? I mean are soldiers psychopaths? They kill, some more than DeMeo, and probably do so without a shred of empathy either, but you don't hear people calling them insane or psychotic.
