As a real estate professional I can tell you the primary reason is the changing demographics of these towns. Generation families living in their hometown are no longer the norm. Families moving in do not get involved in the traditional activities of these towns. Subtle enough?
This is certainly the case for Manhasset, less true for Garden City.
Sadly lots of folks fleeing LI in general. Can't blame them, taxes and commutes stifling, no quality of life. My kids could never afford to live on LI. I'll follow my college bound kid to Florida and never look back.
