well, it's innate in human nature, and this nation's crowning achievement was one of the first nations to have such a free market in the developed world during its golden age. The thing about capitalism is it tends to be successful under a wide range of conditions because humans all do tend to be selfish under all conditions, so it utilizes this selfishness and turns it into productivity, which takes away the difficulty of always having to be altruistic for the good of the nation. At the same time now we are too comfortable with being greedy which is bad for other reasons.