It is estimated that 1 in 25 people have psychopathic/sociopathic traits. That is not to say that they are all serial killers because psychopathy/sociopathy have varying degrees. The person that enjoys making a lot of noise with his muffler may have some need of exhibitionism.
I have been watching a person that I have know for a long time, I suspect that he has is psychopathic/sociopathic. These people place themselves ahead of all others at all cost. They derive pleasure by manipulating people, even if there is no end gain. One trait of the psychopath/sociopath is that the people close to them do not suspect their manipulations and follow them blindly.
One well know case of psychopathy/sociopathy is Trump leading the MAGA people because he is telling them what they want to hear. The difference between a psychopath/sociopath is so subtle that even not all phycologist agree on the difference is. One phycologist believes the difference is that a psychopath is a person that does not care about the outcome of his actions if he achieves his goal. ( Example : He kills to satisfy his sexual needs ) A sociopath is a person that justifies his actions in his mind. ( Example : He hits someone on the head with a hammer because he has been insulted. ) Phycologist believe that psychopaths/sociopaths can not be reformed. The psychiatric therapy applied to psychopaths/sociopaths pre 2000 use to be to try to make them understand the harm they have done but this only heightens their delight in their wrong they have done by reliving the experience in conversation. Reliving the experience validates them in their own mind.
If you suspect you know a psychopath/sociopath, do not allow them to know that you know. They will intensify their cruelty and manipulation on you. If you are aware, the best course of action is to minimize their success in their manipulations and they will apply their manipulations elsewhere.