I think that you missed OP's argument - they're arguing that "wealth" and "social class" are orthogonal. Neither of the two would see each other as their social peer since they have neither wealth nor class in common.

* PhD barista: Low wealth, high class

* High-school educated trust fund baby: High wealth, low class

This sort of framing does seem very medieval though - I get mental images of rich merchants and indebted aristocrats when reading it.