I have long been of the opinion that one of the reasons for a concenyration of like souls is "PLACE". In my county of Yorkshire there are places where certain types of people gather, some of the "Folkies". One of them is Whitby on the North Yorks coastline. Part of the reason is due to the annual Folk Week in August, but in part it is also that we who go there regularly likr the place, as do those who have already retired there ( plus the people who haven't yet retired, but went anyway ).
Another "place" is Hebden Bridge, which is noted for the number of aliens in flying saucers who visit. It must be a prime place of interest if you have green skin and pointy ears, but I personally do not know why they don't visit Luddendenfoot which is only a few miles walk down the valley.
Quack!