[balance_factor]

It is an old argument, and I think a correct one. Money at the top is mostly spent on capital investment. Capital investment makes commodities which are sold to consumers/workers. Who is going to buy all these things if people are tapped out? You can kick the can down the road for a bit with debt, but if the income split stays the same, that just ultimately makes the problem worse when you reach maximum indebtedness.

In terms of smaller returns, you can see this with cell phone manufacturing. So much capital is on the sidelines that when it sees a chance to turn a profit, capital floods in, a massive infrastructure for building cell phones springs up, and returns shrink. The only exception is Apple, for a variety of reasons including that the initial iPhone was a product of high quality and convenience compared to its competitors at the time.