Due to how their brains are wired psychopaths are incabable of feeling empathy and they have no conscience. The only thing keeping them in check is the fear of being caught and punished. Whenever they think that they can get away with ruthlessly exploiting others they will and sadism comes as naturally to them as breathing. They are genuinely incabable of selfless deeds and expecting them not be evil is like expecting that an epileptic won't go into convulsions if you flash a strobe light at them or being aghast at an autist for not having great charisma.
They are essentially like demons in their psychology.
The best thing for humanity would be to excise this disease from the gene pool before its carriers consolidate their power past a point of no return. Even compulsory gene sampling and forced sterilizations would be justified in this.