Users and lots of them? There's nothing sadder than an empty forum and most start empty and remain that way.

In this day and age forums are on their way out unless already established. People do Facebook groups and IM stuff like Telegram or Discord. I think it's an unfortunate development as all that info effectively vapourises.

If I were starting one now I'd be looking to integrate features you see on social media like news feeds and price tickers would certainly tickle users.