Extremes of Socialism (USSR) or Capitalism (USA) rarely last for more than 3 generations. USSR went down first and the US is now on the 3rd gen, nigh last, of it's extreme version of Capitalism. A blend of the two, Socialist Capitalism, may be a stable form that is yet to be tried in earnest however it is being dabbled with in China.
Fundamentally, capitalism is curbed by maximum earning limits for companies or individuals, thereby trying to avoid the pure capitalism motto of 'greed (at the expense of everyone else) is good' whilst simultaneously avoiding the socialist syndrome of 'living of other peoples money'.
Thoughts?