After having dealt with a number of the type, I've come to the conclusion that there is a predatory subspecies in humanity that needs people to pick on and that would do everything in its power to ensure that their prey remains with them or within their striking reach.
Typically this predatory subspecies has lots of stated reasons for its behavior. The main one is portraying their food as evil or dangerous, thus deserving of being preyed upon. Not only do the members of this subspecies drill this concept into the heads of their food in order to keep it; they drill it as well into the heads of other people, denying their food a way out.
Many members of this subspecies find their ways into positions of power and authority, where they can keep preying on people in the name of law, religion, family or the country. Overtly the worst wind up as prison guards and make a career out of sadism. But we also see similar predatory behavior in any number of judges, teachers, policemen, priests, imams, mental health professionals and social workers, as well of course as any number of people who become parents.
This predatory subspecies is driven by two considerations: Being able to prey upon people, and being able to get away with it. Their strategy toward the latter is to prey on people in ways that other people see as legitimate. While some of these qualities are found in any number of people who become criminals, the criminals are amateurs at this trade; whereas prison guards, teachers and judges are pros. A professional will beat an amateur in most cases; and the more effective predatory types find ways to do it legally and with the sanction of society or community behind them.
The professional predators therefore rarely get called on their behavior; and the people who do call them on it are typically subjected to danger. Which means that most of these people not only get away with it but get to claim that they are doing it for the sake of everybody else. Confronting a professional predator is therefore more demanding than is confronting a criminal; and the worst of the type don't wind up behind bars but rather running society.
There has been research in recent years into the sociopathic personality disorder; but I decline to state that these people are sociopaths. I've known one person who had that diagnosis, and she did not do things of this sort. Whereas, with say police corruption, we see it done by whole departments and then not done by them any longer when credible efforts are taken to correct the problem; and it would be unlikely that, in those situations, the entire police departments consist of sociopaths who then stop being sociopaths when they are put to scrutiny for their misdeeds.
The most effective predators therefore become authority figures and learn how to prey on people with others' approval. The school bully becomes the policeman, the politician, the judge, the defender of the community, the military personnel. The immature form of predatory behavior becomes the mature form of predatory behavior. And this predatory behavior becomes a vast influence in society to turn it into the worst thing that it can be.