Corporations make profits if their products are worth it to people, true. But in a sufficiently unequal world, what's "worth it" to a rich person matters more in the market than what's "worth it" to a poor person - the rich command more money than the poor. If the money made by corporations accrues only to a few, we get a positive feedback cycle of inequality: corporations cater to the market; the market caters to rich people; and in a highly concentrated market, only a few people get rich off of this. The result is a poor underclass. Society as a whole gets richer, perhaps, but very unevenly. Besides causing political instability, this is also an inefficient allocation of resources - an additional $1000 improves a poor person's life more than it does a rich person's.