Don Boudreaux says it well:
Here’s my summary take on this issue [income inequality]: unless someone steals from you, you have no business fretting over how much money that person has relative to how much money you have. If you insist, absent any such thievery, on fretting over such a thing, you are deeply immature, excessively materialistic, and obnoxiously antisocial – and, thus, unworthy of having your opinions taken seriously by serious people. (Envy is an unsound basis not only for government policy but also for personal ethics.) And if someone did steal from you, then what you should fret about is that person’s thievery rather than about his or her monetary wealth relative to your own. After all, if the thief’s theft raised his or her income to a level more in line with your own, you surely wouldn’t shrug and excuse the thievery on the grounds that it helped to equalize incomes – and you’d be appalled if the police did such shrugging.