While studies show that at least half of us believe in ghosts, there are not many people in my experience who want to talk about them, and most people are hesitant to open up about their experiences in front of co-workers, for example, because they don't want to be ridiculed behind their backs or not taken seriously in other areas of their lives. There are probably many people out there who were like me for years, privately interested in the subject, but with no one to talk to about it.
If you go into a forum with clear vision and reasonable expectations, it can be fun and informative, but don't expect too much. Forums are made up of people and we all know what people are like!
When I first joined a ghost topic forum, it was fun, but frustrating, because most members were unquestioning believers, downright starry-eyed, and I was a questioning believer looking for proof. It occasionally became a collision of contrasting views, between faith and science, as though the two views were irreconcilable. I finally found another group that leaned more toward analysis, but even there tempers sometimes flared between strong personalities and there was pressure to constantly vote for the site so that it could get noticed and get awards (which are totally made up, meaningless, and given out en masse by other groups also wanting to get their names noticed and move up in the lists).
Forums allow you to express yourself as anonymously as you wish. You make up a username. You can even put out a sexy photo of an elf or fairy princess or a crazy kitty that looks nothing like you, so it's a little like playing dress up and make believe. This is also a drawback, because you have no idea what anyone is really like, and it takes a while to get to know people through their posts, and even then you can't tell if they are being sincere or not. Most forums allow for PMing (Private Messaging) so the same person who is being sweet to you in the public thread may be saying nasty stuff behind your back. Remind you of high school?
Forums are quick to welcome new faces, so you are assured a friendly, even effusive welcome, and it can be nice to experience the friendliness of near strangers after a rough day at work or when you are feeling under-appreciated by your family. It's amazing how much you can have in common with people halfway around the world from you. I've seen genuine friendships form, but I've also experienced cattiness and that whole clique thing that was so annoying in high school.
Forums, especially about paranormal topics, such as ghosts, attract all kinds, from the skeptical to the gullible, from the sane to the emotionally unstable, from those who take it much too seriously to those who join to heckle. Forums are about expressing opinions, and you know how people are about their opinions. If you are the kind of person who has to be agreed with, don't join a forum. Be a bore around the water fountain at work or the dinner table at home. Don't take it online. If you are open-minded and can accept that others are not going to agree with you without getting upset or doing a Ruby, then you may do okay, unless of course, you run into a Ruby.
My advice? Choose your forum carefully and keep some emotional distance. Observe for a while; read what others post; see if the kinds of topics covered fit your areas of interest and if the opinions posted reflect intelligence, respect and common sense on the part of the community members. Don't wear your heart on your sleeve or believe that people on the web are any different that the people in your real world. Practice the Golden Rule and hope that others will do so, and remember to be kind even to those who are not kind to you. (Easier to advise than to practice, I know!) And you aren't joining a cult or a religion, so if the forum proves not to be a good fit, it's easy to move out and move on to something else. You could even try blogging!
Final word: Beware of sharing personal information. The Internet is a public place. Nothing is private once it has been put online.