One thing I've realized is that if you actually do succeed in creating a strong community, there's a good chance it will raise the property values and appeal of your surrounding area and therefore the property taxes and rent for those in the community living nearby and possibly the community space itself, if the space isn't owned outright by a non-profit organization. Then you risk getting bought / pushed out by outsiders that just want a "safe neighborhood" or an "artsy area" and not really a community.

It seems like these social groups -- besides needing a non-financial mission, shared rituals and beliefs, and some kind of exclusivity -- need a strategy for dealing with the social connection-dissolving "market" that exists around it.