Moving to a new location triggers interesting effect in many people - they shed their social fears and laziness and try to socialize more. Living in a hub that attracts many such folks gives one an endless stream of people that are looking for friendship, consciously or sub-consciously.

The drawback is, long term retention is not high in such a location. Its not nice to see people with whom you connected so well leave. But its endlessly better than some stale rural place where you either have really close people from childhood/school years, or you are pretty lonely.