They are very dangerous because they are very persuasive. This is because their psychological condition makes them feel unconstrained by a moral system or even by reality, and also makes them feel that their personal desire of the moment is the most important thing in life and entitles them to do whatever they want.
In terms of philosophy, Obama is Nietzsche’s “Superman” (UBERMENSCH)- a creature “beyond good and evil” who Nietzsche believed was the final evolution of Man.
Of course, Nietzsche went insane. Perhaps because he realized his UBERMENSCH was not an advanced evolution of mankind, but the same old psychopath the honest man has done battle with since the Garden of Eden.