[twoodfin]

I think throughout the last 40 years or so we've gradually become so accustomed to the diminishing size of the middle class. We don't realize what it used to mean. We forget that a time existed where a family with a good budget could live on one income and still afford a house, two cars, college funds for the kids, vacations, and savings.

The middle class has "diminished" in large part because more households rose into higher income levels[1][2].

Many households could still live on one income, but choose not to because the opportunity cost of not working is too high: Mom and dad would both rather have the money, go on international vacations, eat out more often, take yoga classes, buy more gizmos... All stuff that people did much less of 40 years ago.

[1] http://www.cnbc.com/id/48754974

[2] http://www.aei.org/publication/yes-the-middle-class-has-been...