The problem isn't capitalism or free markets. Hell, we've never had the later and as for the former, only barely. To the OP, you seem to be under the assumption that wealth is finite. It isn't. True, there may be a finite amount of wealth in existence at any given time, but there is no ceiling on potential wealth.
It can be created through sacrifice (i.e. a man forgoing a meal every other day to save for a bike), and through ingenuity (someone inventing a more efficient means of producing something--the cost is the same or less, but production is greater). When left to their own devices, sans government (or religion, or any other polity) imposition forcing a certain way of life, humans in general are upwardly mobile. People can and do make short term sacrifices to improve their station in the long run--it's essentially what happened with every minority group in the US (albeit to a lesser extent with the African American population, but that's due to what was a concerted effort to marginalize and manipulate them post-slavery. It is only when the government interferes and whittles away at your savings and the produce of your labor through wealth consolidation tactics such as inflation and taxation, or through manipulative and biased regulation and legislation, that upward mobility ceases to be an option for the average down-and-out.
And that is not to say that Government, or Religion, or Megacorps are inherently evil. It's just that they are monopolies. A monopoly of force, a monopoly of thought, and a monopoly of trade. And as with any monopoly, they are prone to corruption. Capitalism is no different. Or communism for that matter (although I would say the major downfall of communism is that all three monopolies are contained within one political entity--the State). Right now, the U.S. and the Capitalist world in general are corrupt. But that just means we have to be a little more vigilant in stamping that corruption out and paying heed that it doesn't crop up again thereafter.
There will always be corruption, no matter what monopolies we choose to replace the ones we have now. And it is the eternal duty of mankind to stand watch against it. For a world without corruption can only be to things: a fairy tale or a nightmare. The first is fiction, the second is science fiction.