The "income gap" is a problem only because people are told it is. It's a purely perception based issue. The disparity between rich and poor in the US is growing, yes, but the quality of life at all levels is also growing, even the lowest. The gap has been going only because the rich have been getting richer faster than the other groups. This does not mean that the other groups have been getting poorer, or declining in standard of living. Quite the contrary, the standard of living has been continuously increasing everywhere.
This is where the marxist inspired economic egalitarianism falls apart. It assumes a 0-sum economic game where one must inherently loose for another to win. Historically, though. industrialization and profit-seeking scientific advancements have allowed all participants to benefit from trade, even if some benefit more than others.
If we stop worrying about the other guy's glass being overflowing, we'd notice ours has been filling up too.