Paul Krugman:

“If you look systematically at the international evidence on inequality, redistribution, and growth — which is what researchers at the IMF did — you find that lower levels of inequality are associated with faster, not slower, growth. Furthermore, income redistribution at the levels typical of advanced countries (with the United States doing much less than average) is “robustly associated with higher and more durable growth.” That is, there’s no evidence that making the rich richer enriches the nation as a whole, but there’s strong evidence of benefits from making the poor less poor.. Incentives aren’t the only thing that matters for economic growth. Opportunity is also crucial. And extreme inequality deprives many people of the opportunity to fulfill their potential. Think about it.“