this isn't true now, but it was true twenty years ago that geekhood was the place for socially awkward outcasts. bullied by the jocks for wearing glasses and the geeks would take you in. it still has that image to some degree.

it's probably self-perpetuating. put a lot of socially awkward people together and they'll keep the same dysfunctions rather than learning better.

i suspect the root of it is in such people being strongly drawn to escapism, and fantasy/sci-fi is a particularly potent form of it.