Wealth distribution, simply, is one of the largest contributors toward "the great world problem." I forget the author, but it's a great quote: "If I give the poor food, they call me a saint. If I ask why the poor have no food, they call me a communist."
Another would be laws: most of the world is full of underdeveloped people that won't behave if there is no fear of social shunning/social retribution (laws)/etc, and the other 1/3 that cares about developing beyond this fear (and doesn't need laws and fear to behave ethically) requires rules to be flexible and allow for some degree of mistake. In the words of Aristotle: "I have gained this by philosophy: that I do without being commanded what others do only for fear of the law."
Capitalism, in practice, is a very flawed system for the same reason: it is, in theory, supposed to encourage innovation, self-improvement, and "the best product." In practice it turns out that those that prevent innovations (oil companies preventing the electric car), are greedy bastards that don't self-improve, and don't have the best product, but the market shares to outshine any competition are the ones that wind up succeeding. Not to mention the extreme gaps in inheritance inequalities...some people have clear advantage from the start.