All of the wisdom is contained in these words. If your interest happens to mix with a market need, you have something to start with. Mix in creativity, a temperament that allows you to grow and not destroy a forum, and an unhealthy amount of energy and drive to build something that will never pay you back properly for the time you put in, and you have a shot at "success."
I disagree. General forums are a sure-fire recipe for failure, from my experience. The problem: people don't go on a forum to discuss just anything. Plus there's always the problem of traffic: If you start a forum about everything, you end up with huge pockets of talk about nothing, for people follow the crowd, and it's tough to get a crowd around a forum about everything.
As to the particular forum you link to, I see a bunch of one-post threads. Plus all of those "members" at the bottom of the forum look fake (they all have 0 posts). The trouble with trying to tempt "real" people into joining a forum filled with fake members is that fake members don't post content and have real discussions, which is what would prompt real people to join.
The biggest problem with a forum no matter what it is about is getting over that pivot point with content and members. Most people are not interested in building up a forum or contributing to one that is being built up. The come in join and see not content and not much post movement and leave. So the question is how do you get overt that point where your members base and post count per day is enough to make others stay once they join. You can have 100 members registering per day and then finding out you have a slow moving forum and they just leave. You end up with a huge member base and little or no real forum movement at all.
Most people join a forum to get something out of it as in information or some type of reward as in prizes. Once they have what they needed from it they will leave unless you really have something to keep them hooked on your particular forum.
So what is that golden rule that make a forum work, not many people know! Unless you have a huge amount of cash to put into it as far as prizes and other free stuff you will battle to get over that pivot point unfortunately. Have a look at my new forum Justbikez I have people signing up sticking around a few days and a few post then they gone.