NYC wasn't only poor people (it's a major business metropolis of ~10MM people, not everybody is going to be poor), but it was actually affordable on a small income. In fact, most of the US was the 80s, and 90s. Don't know what you mean by the Puerto Ricans who lived there before her, because they're still there.

You're right that NYC is still somewhat affordable if you look outside of Manhattan, not Crown Heights though, but places like south Brooklyn, and east Queens. The issue is that everybody who's never lived in NYC, or only lived there after getting a college degree only considers NYC to be Manhattan + Williamsburg.

Source: Growing up poor in NYC.