> By this, I believe he means private-school, summer-house, frequent-flyer-miles-in-your-early-20s rich.

The example given literally attended one of the top private art school in the world. The reason people are reacting is likely because of this often damaging non-differentiation of being temporarily and perpetually poor. Many people can't even afford to move to a city these days, let alone start a startup. And if they do it might have negative consequences for years and years.