Well, we already have an idea that the U.S. is on its way to becoming a plutonomy--an economy dependent on the spending and investing of the wealthy. Now, we have some numbers to back it up.
In a recent article in the Wall Street Journal by Robert Frank, the top 5% of the Americans by income account for a whopping 37% of all consumer outlays, which include consumer spending, interest payments on installment debt and transfer payments. By contrast, the bottom 80% by income account for only 39.5% of all consumer outlays.
And the thing is, this has been the pattern of the last 20 years.
This trend would have been okay if we find the ideal pattern of development where eventually, the middle and lower classes would shrink and move upwards. This, however, has not been the case. For the top 5% by income, they're share in consumer outlays was 25% in 1990. Since then it started to inch up to 30%, until it found itself having a larger share of the pie.
The recent recession doesn't help either. According to the article, the middle- and lower-income groups are struggling to pay off debt and stay afloat amid rising unemployment.
Of course, this reflects the other ugly side of income inequality, which has been the main economic contribution of economists Emmanuel Saez and Thomas Piketty. As of 2007, they find that the top 10% of earners captured about half of all income.
It is really something to worry about. We've already arrived at an age where massive social unrest is rare in developed economies. The U.S. might be heading that way.