None of their fans are going to want to see all of their time taken up by community engagement. Some, certainly, are clueless, and enjoy being time vampires. You deal with time vampire 'fans' the same way you deal with time vampires in real life.
If you have an issue with the time commitment, make a rule for yourself and stick to it. "I'm only going to visit the forums on Friday nights." Or something similar. People will give you a wide berth, especially once your forum reaches a decent size (more than 10k members or so). Maybe a bit too wide, even.