The growth of inequality is definitely a bad thing
Lets say you and I start with income of 50,000 for me, 100,000 for you. 10 years later your income increases 5 X to 500,000 and mine only doubles to 100,000. Am I worse off?
The whole idea that income inequality is bad is based on the idea that there is a finite amount of wealth. PJ O Rouke used the old pizza anaolgy.
But income doesn't work that way. Also these people fretting over income gaps or stagnating wages never seem to account for fact that middle class people live much better lives overall. That we can afford more and better stuff because real costs are generally lower.
Not to mention a lot of these studies are based on household income but don't consider the factor that household size has drastically changed.