Have you not seen the explosion of consumer debt over the past decades? Buying power is now tied to how much a bank is willing to lend you, not how much you have in your savings accounts. Synchrony, who Amazon partners with to offer their store card, will give basically anybody with a pulse a $500 credit line and ramp them up to thousands fairly quickly as long as they don't default.

I don't even want to get into the real debt traps targeted at the least fortunate among us like payday/title loans, buy-here-pay-here car dealerships, etc.

With increased income disparity, the top can make up for the bottom on domestic consumption metrics.