When one looks at the number of people in the US who feel the need to medicate themselves with mind-altering drugs in order to live and function, I think it becomes painfully clear that we have an insane culture; a self-destructive, self-predatory culture based on the irreconcilably contradictory mores of capitalism and Christianity. The teachings of Jesus are antithetical to the dictates of the capitalist market society.
I will agree in part with your comment. I do believe that our culture has gotten out of control with the "rich getting richer and the "poor getting poorer". The modern world has bought into the illusion that capitalism has benevolence built into it. (News flash: It doesn't). The problem is that human nature, as you pointed out, can be self-serving. If an executive receives yet another million dollar salary increase, what would compel him or her to say no? Nothing.
That being said, I believe capitalism is still the best economic option at this point in time. Human nature, as a whole, is not a point where we can realistically and logistically follow any other economic option. Despite all of its flaws, capitalism has led to the economic and social rise of many more people than any other economic philosophy. Capitalism, at its base, offers an opportunity, which options like communism and socialism do not. Even if one accepts the ideals of communism and socialism, the implementation of those ideals never reaches the light of day.
Early Christianity, from what I have read and studied, was an amazing point in history where economics were used as a tool to demonstrate God's Kingdom. This is what I think you were referring to when you mean "the teachings of Jesus". In those early days, disciples gave away half of their wealth (in addition to tithes and other offerings) and developed a system of administration that supported the poor. If the world were to truly embody that philosophy, we could end poverty today.
Unfortunately, that didn't last.
The key flaw in capitalism is human nature, which can only be changed (if you believe) by Jesus. Once that is changed, it won't matter what economy you are under, because you will be connected to the most abundant thing in this universe.