Age of the robber barons was briefly interrupted by Great Depression, but greed of those who managed to hold on to their wealth and avaristic basis of capitalism has led us to deja vu age. Oligarchy is inevitable when capitalism isn't balanced with a bit of more altruistic socialism where sharing the wealth, ensuring those who keep the money flowing up are, at the very least, able to feel appreciated and not have to worry about what happens to them and their families should they no longer be able to work or need to retire.
Repubs and corporatists have worked to shred social safety nets put in place in 30s instead of improving them. The War on Poverty has become War on the Poor. Unions had much to do with building America's great middle class, but instead of accepting the logic that corporations need customers who can afford their products, capitalistic greed sees them as impediments to the unnecessary amassing of wealth for those at the top. They see fair wages and safe working environments unions try to ensure as dreaded socialism, ignoring that democracy requires capitalism be kept in check.
Paying back to ensure the system that enabled the wealthy to gain their financial security is all modern socialism is. Sharing the wealth, a bit of altruism, keeps the system working instead of the feudalism that inevitably leads to rebellion that occurs when capitalism runs free and unrestrained. If the altruism needs to be a bit forced upon those who can afford to share their wealth, so be it. Our claim of democracy as a superior system of government requires a little socialism.