For one thing, the vieux riche inspired entire revolutions with their compassionless, ridiculous, indefensible behavior. The wealthy nobility is a primary reason why so many countries are now democratic.

Clearly "being a complete dick" is not the exclusive purview of the nouveau riche. The notion that people who inherit their wealth are less likely to abuse it over people who earn it quickly also doesn't pass a lot of mental muster.

The distinction between "nouveau riche" and "vieux riche" smells like (and is) a classi No True Scotsman.

This is exactly it. If one is born into money, the sense of entitlement is in-bred and it doesn't need to be asserted explicitly, leave alone aggressively.