Like many, you have got your suppositions mixed up in cheap karma.
Income equality (not income inequality) stunts growth, for the value of even our minute differences, is more meaningful to our evolution than the value of our stifling commonalities – making income equality not only an inherent oxymoron but an evolutionary lie.
For no people are the same, and appraising them as such is the systematic denial of the innate complexity of their unique composition, and the opposite to what nature’s evolution ultimately has in store for them and vice versa.
And it is in the interest of the longevity of our species not to taunt nature but to learn and abide by it.