This one's not about IQ. Listen up.
All human traits are normally distributed, with few people on each extreme. I don't know to what degree character is inherited, but it sure as hell is innate.
A human trait, like any other, is the thirst for power. Call it sociopathy to get a better image. It's probably not the same thing, but think of the evil striver who lies, fools, scams and does any manner of evil in order to climb the ladder of power and get to lord over others and enjoy riches gained through the exploitation of the people.
Think of Clinton, say. Any of them will do. These guys have an edge. They're driven. They really really want power. And money. Lots of money. Apparently the Clinton's are worth $100 million. Why do they want so much money? Isn't $10 million enough? 20? No, they want more. That's what they do, they seek power, money, and everything that is nice, they seek it in infinite amounts. Why does Hillary want to be president? What for? The satisfaction of power. That's who she is.
But she isn't the only one. There's lots of people like her, in any country, in any institution. Jerry Pournelle had the Iron Law of Bureaucracy: every organization will always end up being led by people devoted to the benefit of the organization, not to doing whatever purpose the organization originally had. Which is another way of saying that any organization will eventually be led by people who only think of benefitting the people who lead the organization, i.e. themselves. The greedy power-hungry. Let's call them Clintons, for lack of a better word. Every organization will eventually always end up being led by Clinton's. Simply because they take care that they end up ruling. They seek power will all their heart, and they get it. That's how you get Conquest's Law too. All organizations not explicitly rightist will always end up turning leftist. Why? Because the left is simply what the Clinton's do. The Left is whatever works at achieving power and keeping it.
In any Open Society™, well all positions are open. There is no privilege of birth, no traditional standards. There is to be open competition. Even the upper reaches of power are to be open to everyone, by free elections. Democracy. Who wins in a democracy? The Clintons. Why? Because they seek power, and have no qualms at doing whatever is necessary. Fraud, lies, treason. Murder. Whatever it takes, they will have power. That is what they do. Remember the Selfish Gene? The Hawks and the Doves? Hawks are evil, they hurt everyone. But you can't get rid of them. They're never too many, else they start killing each other. But at small numbers they always win. Michel Houellebecq first became famous with his novel, The Extension of the Realm of Struggle (Whatever). He points out how opening the sexual marketplace to competition advantages the ruthless and evil, to the detriment of everyone else. That works in politics too. The right edge of the Bell Curve always wins.
In a traditional aristocratic system, positions of power are given by family prestige. There is some level of striving and merit involved, but mostly it's old families sharing positions of power according to traditional standards, which nobody really understands why are there. Mostly reflecting old Schelling points left by ancient conflicts. But they are there, and they are never touched. You don't get to a position of power if you aren't of the right blood. A Clinton can't get to president. He can join the staff of some aristocrat, and schmoozing him to achieve influence by proxy. But you can only get so far that way; and positions in the staff are also subject to traditional limitations. There's a firewall there.
Traditional power arrangements can be stupid and ineffective. They are by definition nepotistic, and often nothing gets done. But they have the important function of impeding the access of evil sociopaths to the highest reaches of power. You really don't want those people up there; all they do is suck the coffers dry, and hurt everyone they fancy in order to satisfy their greed. Democracy, by opening the levers of power to free competition, all but guarantees that evil sociopaths will end up ruling everything. People who have no issue with giving sick men access to girl's toilets, or bringing hostile barbarians to rape the women of their country. Monarchies can have a bad king. But Democracies always have a bad king.