I once read somewhere that the issue is that to the old rich money isn't a topic. It's something that exists and has existed for a long time, that gets used when needed, but doesn't get talked about.

New rich on the other hand feel the need to display the fact that "they've made it", talking about money is important to them.

So there's a certain incompatibility between old and new rich, where old rich feel bothered by the talk about money.