Yeah, and even hard work and energy isn't enough - all the really active fan comms that I remember on LJ got a boost early on by being promoted by bnfs with huge followings - the old-school version of viral, I guess - and I've known people who put in months of devoted mod effort and got nothing because they didn't have the luck and connections

That said, there are some DW comms that have managed to stay active due in large part to the mods' hard work! There are several writing communities I know of like that, to start.