Thanks.
Totally agreed that forums (and communities in general) have the cold start problem, and there's no real good solution for it.
I do have some ideas though.
1) I'm interested in whipping up a simple phpBB mod that enables Link posts (like here on HN). That will help with the News posting aspect of the community. Thread here: https://hackerforums.co/the-lounge-f3/idea-extension-for-php...
2) I'm going to write up a fairly detailed thread later today that explains in more detail the Why of setting up the site, and the How I did it (literal technical details for those interested). I'll post that here and on Reddit and a few other places to hopefully get some exposure. Cool kids call that "traffic leaking" where you get valuable content in front of active communities, so might drive some traffic.
3) I'm debating setting up a contest of sorts, where members can earn a special badge/title by actively participating in the forum. So for example, start 10 threads and post 25 replies in threads and earn a special badge on your account for eternity. Silly, sure, but could be a simple fire starter.
But yeah, overall, it's a challenging thing to do, and I've failed at it a few times over the years in trying to start forums. I still really love them though, so I wanted to try it again.
BTW: Post your project here! :) https://hackerforums.co/show-hf-f7/