I think this could become possible if some sort of organism or infection caused the disorder. In this case, if the organism or infection is transmittable, an epidemic could be one possibility. As there are many contagious diseased that directly affect the brain, I think this scenario is certainly possible.
It is my opinion that an epidemic of a psychopathy is not possible. I do not feel that this condition can be spread from person to person in the way that a virus can. Therefore an epidemic of this nature is not at al likely to occur. This is a mental condition that is not contagious.
I doubt things like the movies or TV shows that push these ideals around would ever happen. I think you have to worry about one of these kinds of people, finding a power role. The past has shown that they can do real damage to the world, I doubt a gang of them will ever exist though.
A psychopathic illness is an illusion. If there is an epidemic of psychopathic behavior, it has to have some sort of root cause within environmental factors. An epidemic of psychopathic behavior isn't due to some kind of disease or mass hysteria. There could be some kind of water-borne pathogen or airborne virus causing brain damage.
I am by no means an expert on this subject. I do believe I have heard there is gene that people have that causes this type of behavior. That and they might have some mental problems on top of it. The real sad thing is some of these psychopaths are running the country. If You ever wonder why some of our leaders seem so heartless. It is probably because they are psychopaths.