Communities don't scale. This is the reason why nobody has done and why you couldn't get rich forming communities. Communities are handcrafted to accommodate the unique personalities of the people involved. Communities involve activities where a handful of people can socialize and bond. A service with a million users can never become a community because our social/grouping instincts don't work on that scale. A community should always be a few dozens of core people, with maybe a larger number of non-core people participating occasionally.