Every society - EVERY society - allows some people to rise from the underclass to the ruling class. In the Roman Empire there were, from time to time, senators and other high magistrates whose grandparents had been slaves. That does not make slavery okay. And for the same reason, the fact that some lucky few manage to rise to wealth and fame in the US today does not make poverty okay.
Liberals think that the only problem in capitalism is that the poor don't deserve to be poor. But the bigger problem is that the rich don't deserve to be rich. The richer a capitalist is, the greater the likelihood that he is a merciless sociopath. Remember that the next time you see the media fawning over some "successful entrepreneur". Chances are, that man is a monster.
