Interesting. No doubt people are making more then ever before, but I think their data is a bit skewed. They define household income > $100k as "rich" (the Census Bureau says >$150K is "high income.").
Middle Class Shrinking… As Households Become Richer
I don't know of any two income families where both parents make $50k (say, a nurse and a mechanic) would classify themselves as "rich."