Any kind of community can become very addictive, especially to people that are going through a lonely period with a lot of free time.
I know of somebody that's deeply engrossed with Skyscraper City even though she isn't an architect, just because it has an encouraging community and she has a 4 hour commute and works in multiple cities (which makes it very hard to get into an offline community)
To a segment of people, http://www.big-boards.com/, it is their life.