Certain people function as “social magnets”, for lack of a better phrase. They’ll walk into a room and bring the party with them. (In Soviet Russia, the Party walks YOU into a room! …Sorry, couldn’t resist). They tend to attract people in two topologies: mesh (small groups of people interacting with each other) or star (everyone talking to the “magnet”). When they walk into a quiet room and their entourage begins to build, the former inhabitants of that room (who are almost certainly all introverts) will look for an excuse to leave.

This takes place in cities too, except that now we have groups rather than individuals:

Suppose a group of, say, famous musicians decides to buy houses in a specific area (say, Rumson, NJ). The entire town will attract fans of the group, who will find common ground interacting with each other about the musicians, or will interact with the musicians themselves.

This is a recurring motif on all levels of social organization, and might be worth thinking about in more depth.