From an article in today's NY Times about small apartments:
Typical of the young buyers is Laura Cave, 24, who bought a 450-square-foot studio at 20th Street and Seventh Avenue after moving from California to study graduate-level humanities at New York University. As with many younger buyers in the studio market, Ms. Cave's parents financed the purchase, and she pays rent to them. The apartment is in all their names.
This demonstrates a very important source of high prices in Manhattan. Young people usually get money from their parents to pay their rent.
This is contributing to the new social immobility. Young people whose parents are just middle class can't afford to live in Manhattan and are denied the better career and social opportunities because of this, keeping them forever in the class they were born to.