I agree with Matt, Facebook, YouTube and Twitter have sucked the life out of forums. I have had to revisit my previously deleted facebook account to remind people to revisit my forum, they just forget to go and visit and post and they act like it's a really long walk to the shops and they can't be bothered to visit other sites outside of the big three.
It's bloody annoying, as those platforms don't seem to work in regards to discussions, whereas a forum is set up in such a way where you are there to talk and discuss in depth, instead of sharing gratuitous selfies for randoms to hit the like button for. The language of Facebook annoys me 'my wall' - sounds defensive from the get-go doesn't it? lol
You have to persevere, spend time and money and keep the forum active - I usually appoint relatively new members who stay active and mature as mods and this keeps them posting at least as they feel they have a stake in the forum - OUGC awards also boosts enthusiasm, but a good admin will listen to what users want and be very clear on the rules.
Lounge topics are essential in the beginning in my opinion and a few fake accounts never hurt anyone - I allow and encourage users to have multiple accounts, but it's purely to encourage discussion - one or two members have two or three accounts on my forum, I have three and we basically agree and disagree with ourselves to offer various points of view that others can partake in.
I recommend not setting up loads of sections to fill, keep your forum simple and only add more sections if a particular topic has at least two or three pages of threads that receive replies and reactions. A forum with loads of empty or near empty boards looks silly to new users, as it just looks like you are trying to imitate another forum, you have to allow your forum to become whatever it will become to a degree.
I have seen badly managed forums become very successful, but good members come and go very often because particular groups form tribes and herds, packs and banditry becomes the daily grind where discussion goes out of the window and you end up with a troll pit. Censorship is not advised either, that can seriously cripple a forum, I recently saw an appointed admin lose his position on one forum because he was deleting posts he didn't like or agree with, but I think it was due to him being the star of the show with his own narrative.
Most forums that vanish were spur of the moment without any real concept of what a forum entails or how hard it is to keep maintaining it.
I set up mine because I prefer forums for discussion, all discussions are stored neatly in sections, whereas Facebook, YouTube and Twitter has a fast pace and everything changes day to day and some conversations simply get lost over time when groups are deleted etc, or you just forget where they are.
My forum is just starting to pick up - I installed mybb on new years day and I have bveen on it everyday, there are nearly 2000 posts and 30 members, but only around 6-10 of them are active. I think if I can get to 200 members, the forum will have a life of its own and it will definitely stay online, I really hope it does, as I would hate to have to go back to Facebook to talk about things - it's not really set up for that in my opinion.
If anyone fancies joining, hit the website link or copy and paste my user title. I also recommend doing post for post with other admins and their forums. It's funny how the only people who you can guarantee will be good members are forum owners themselves!