The New York Times has a funny piece focused on an unintended consequence of the super rich having pricy Pieds-à-terre apartments in Manhattan's leading buildings. Some doormen claim that at any point in time only 10% of the building's units are occupied because 90% of the owners are elsewhere. Take a look at The Plaza at night. The picture below must have been taken in Central Park and you can see the famous Plaza as the small (14 story) building in the middle left of the picture. Note that almost all of the lights are out. The owners are not home!
Does this matter? It would affect social capital in the building and it would create something of a "Ghost Town".