Specifically, you sneer at the customs of the people you might be mistaken for.
And they’re worse when it comes to the tastes of people in successful-but-not-intellectual people like sales(wo)men. The vehemence makes it seem, at least in part, like a way to say “I may have their incomes, but I’m not like them. I’m better.”
Two of many insightful paragraphs from Megan McArdle. The article, titled “Rage of the Almost-Elite“, concerns what motivates the Occupy Wall Street crowd, and is well worth reading. Presumably, people are upset for a large variety of reasons, status envy and disappointment being just two of them.