Do the rich work harder than everyone else?

Billionaire Richard Branson says no, that they're just more fortunate than everybody else. But studies on the subject suggest otherwise (as do my own observations of L.A.'s super-rich). From the Wealth Report:

Research by professors Mark Aguiar and Erik Hurst combined the results of several large surveys (including studies where randomly chosen subjects kept detailed time diaries), and found that the working time for upper-income professionals has increased compared with 1965, while total annual working time for low-skill, low-income workers has decreased.

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Research by Daniel Kahneman, the Nobel Prize-winning psychologist, shows that "being wealthy is often a powerful predictor that people spend less time doing pleasurable things and more time doing compulsory things and feeling stressed." His study found that people who earn less than $20,000 a year, for instance, spent more than a third of their time in passive leisure, like kicking back and watching TV. By contrast, those earning more than $100,000 a year (more affluent than wealthy), spent less than a fifth of their time in passive leisure.