Does a psychopath realize he/she is a psychopath? Is it a conscious choice?
That is a good point and a very valid question.
I have known young people who have wanted to be considered psychopathic and been capable of some seriously unconscionable behaviour in an effort to convince others they deserve that label.
I also think that there is a possibility that the idea has been glamourised to a certain extent by film, story and pop culture, objectively speaking no one would glamourise other psychological disorders in the same way or desire to be labelled with them, for instance, as learning disabled or autistic.
In some ways psychopathy deserves to be considered as akin to learning disability, there is not the same popular moralistic definition attached to both disorders, but the abscence of empathy within a psychopath prevents them from experiential learning, they can make a good study of humankind, they can to a good impression of being a human being but obviously the conscience is not there to inhibit behaviour, in the same way that the abscence of other traits of mind in other disorders can result in disinhibited behaviour.
There are not so many true psychopaths around as I believe there are other sorts of psychological traits, which result in the rationalising of human misconduct, things like narcissism, injured pride, inferiority complexes I think drive a huge amount of criminal and evil behaviour, also boredom among unimaginative individuals who already possess tendencies towards cruelty or violence.
Although, something which is worth baring in mind, is that all these exercises in explanation or analysis are viewed as so much wasted, pointless and meaningless theorising by most evil individuals, its the actions of losers, victims and perceived as weakness. A true psychopath may not care either way, they are likely to care little enough to label a thing as evil or good in the first place, at least in any way other than a superficial way.