It's how you view your personal future
I think the article is spot-on. It's all about how you view your future and your prospects of improving it.
Because of the recent recession and the mounting debt crisis, most Americans don't see themselves becoming rich. They see an even dimmer prospect for their kids. As a result, class warfare arguments have never been more successful in politics.
I've lived through several optimistic eras (early '80s, late '90s, early '00s) and several pessimistic ones ('70s, late '80s and early '90s, and now). They all track how well the overall economy is doing and the actual amount each person has improved his or her lot, as well their future perceived prospects.
It's the same for the Chinese. A generation ago, it was an agrarian society where everybody was stuck. Now they're making more money than they ever did before, and see more opportunities ahead.