She had no idea Nick was crazy rich ?!?!?

All wealthy people don't flaunt it. In fact, most of the people flaunting wealth are faking it, and acting rich to assuage their insecurities. Recently rich people, especially those who didn't earn their wealth through hard work, do flaunt it, and typically lose it over time. The majority of truly wealthy people wear inexpensive clothing, drive inexpensive cars, and have inexpensive tastes in food.

Let's remember that Nick was an only child so when he says he always thought of it as "their wealth" and not his that is bullshit. Why would he want all of his family's success to benefit others and not him?

I've never seen the film, and was only commenting that one can't always identify a person's wealth by how they look or act.

True story: years ago, when I was in college, one of the wealthiest, if not the wealthiest, men in Berkeley, California was a homeless guy who was hit by a city bus. He used his settlement check to buy a building half a block from the UC Berkeley campus after having a dream in which the Russian mystic Rasputin appeared to him, holding up a record while saying "dooo it, dooo it!" In 1971 he opened Rasputin's Records in the building, which grew to be a multi-store chain all over the Bay Area. The dreams didn't stop, and one night he realized it wasn't a record Rasputin was holding, but a pizza. He opened Blondie's Pizza in another building he owned just adjacent to campus, and the dreams stopped. He eventually bought many other buildings, and opened many other businesses, all wildly profitable. You'd often see him wandering the streets, still dressed like a bum, muttering to himself, and you'd never know he was worth millions.