I know of folks MOVING to Manhattan for well-paying jobs. So, while the island sinks into madness overall, its has mini-islands of prosperity. Frinstance, Google is growing and hiring in lower Manhattan.
The island is not sinking into madness. The island is Manhattan - the wealthiest of all the boroughs. The last apartment I had in NYC was in “Curry Hill” (east 25th Street) around 2011 and my neighbors, actually, were all middle-class people.