"philanthropy is about more than just social responsibility—it’s about social stability."
So other than a genuine desire to do good or vanity seeking that can motivate philanthropy, you have a third element in China - preventing a revolt by the poor on the rich. If you give just enough, you'll keep the poor subdued.
I wonder if there are similar motivations for super rich American philanthropists. My guess is they're less worried about revolt and more motivated by vanity.