Politics and Economics

The same human factor works behind our Our government and our economy.   In American democracy, people have always voted for their own self-interests (real or imagined).
The tyranny of the majority is a real phenomenon; it's part of the reason I like our judicial system so much.  The courts check and balance the voters.  
History doesn't support the idea that a democratic vote is supposed to be cast for the benefit of the many

People have continuously voted to take rights away from others.
We can see this now with measures like prop 8 in CA or any other state where voters deny people the right to marry.
Looking back to America's birth, the government has always written laws to give power to the wealthy elites.  First by restricting the vote to white, male landowners.  Then created laws that gave more power to slave-owners.  Used Armies to force tribes out of their homes.  Created laws that made women subservient to men.  Then created laws to allow segregation. Etc.
All this making it easier for the wealthy elite to gain power.

Democracy, capitalism, socialism... all ideals that assume people are benevolent.

"How selfish soever man may be supposed, there are evidently some principles in his nature, which interest him in the fortune of others, and render their happiness necessary to him, though he derives nothing from it, except the pleasure of seeing it."

"And hence it is, that to feel much for others and little for ourselves, that to restrain our selfish, and to indulge our benevolent affections, constituties the perfection of human nature; and can alone produce among mankind that harmony of sentiments and passions in which consists there whole grace and propriety.  As to love our neighbour as we love ourselves is the great law of Christianity, so it is the great precept of nature to love ourselves only as we love our neighbour, or what comes to the same thing, as our neighbour is capable of loving us"
Both quotes from Adam Smith's Theory of Moral Sentiment.
Every time I see someone speak of Adam Smith, I seriously doubt they have read all his writings.

I think cartels depend on the government to enforce laws that benefit them and ignore laws that are to their detriment.
I think we really will never know what the outcomes of capitalism or socialism would be because the ideals we imagine don't include the people factor.  Ideals ignore the ingenuity of the greedy;  And ignores the human tendency for hierarchy.