The poor are making poor choices. Right?

I want to read more deeply into this new paper about how debt is swamping the middle class—which makes the suggestion that the leverage problem is holding back America's economy. But in a quick overview, I couldn't help but notice this:

• The debt is highest among the middle class. Middle-income families before the crisis had a debt-to-income ratio of 155.4 percent in 2007, the last year for which data are available, for families with incomes between $62,000 and $100,000, which constituted the fourth quintile of income in our nation in 2007. This ratio is higher than for any other income group. Families in the top 20 percent of income (with incomes above $100,000) had a ratio of debt to income of 123.6 percent, and families in the third quintile (with incomes between $39,100 and $62,000) owed 130.7 percent of their income. Households in the bottom 40 percent of the income distribution (with incomes below $39,100 in 2007) owed well below 100 percent of their income.

In the Facebook thread on my payday loans post yesterday, there was some discussion—typical in these circumstances—that the poor are poor, and dragged down by the burdens of debt, because of the poor choices they make. And in some cases, I'm sure that's true. But honestly: It appears that the low-income folks of America might be the only ones not taking on far more debt than they can possibly afford.