Do mean besides the hoards of research linking larger income inequality to lower growth: http://www.imf.org/external/pubs/ft/sdn/2014/sdn1402.pdf http://www.nytimes.com/2014/08/06/upshot/alarm-on-income-ine... http://www.sciencedirect.com/science/article/pii/00142921950...

Not to mention the marginal value of dollars to the hyper rich is substantially lower.

The wealth/income distribution we have now looks very different than it did even 10 years ago, so it is worth discussing as a society what the 'correct' distribution should be. Hedge fund managers now are no better than the managers of 10-20 years ago, the system has evolved to favor them more.

We can argue about whether they 'deserve' said wealth, but research shows that the wealthy need a given dollars less than the impoverished and growth can benefit when the distribution is more equal as well.