By Derek Thompson, writing in The Atlantic. (The title is so bad: "The Free-Time Paradox in America/The rich were meant to have the most leisure time. The working poor were meant to have the least. The opposite is happening. Why?" I hate the use of the word "meant," and the article is mostly about men who don't work, so "working poor" is bad.)
Theory #1: "The availability of attractive work for poor men (especially black men) is falling, as the availability of cheap entertainment is rising."
Theory #2: "Social forces cultivate a conspicuous industriousness (even workaholism) among affluent college graduates."
Theory #3: "Leisure is getting 'leaky.'" (That is, work leaks into leisure time through our wonderful gadgets.)