A forum website can be made in a day. Your requirements so far right now just seem to be "saidit" with moderators. You could do that and just sit by yourself making posts to yourself on a forum all year long.

That's the thing about social media giants, twitter, facebook, instagram, etc. You can make an excellent professional alternative (think Google+), and no one will ever use it because it hasn't gone "viral". Not only is an idea not enough for a successful forum, a well-executed plan is not even enough. Google tried it.