I was part of a now-dead "threaded message board", which had a somewhat cliquey view of what should/shouldn't be posted. In the evening when the moderators were away, the discussion became more interesting as it strayed off-topic.
Eventually the community wanted 'to fork' so I decided to build something myself. I'm not IT trained, so first version was PL/SQL on Oracle - all I knew. v2 was the product of me buying an O'Reilly PHP/MySQL book (I still have 'platypus' somewhere).
People came.
First few years were a mess. The more technically literate people used to hack me for fun - but then would confess and provide security tips.
As the mood took me I'd add features, and then if they became troublesome fixed/killed them.
The odd person would arrive and cause trouble, and I'd have fun working out how to make them stop. (correlate logins with emails, password, IPs, browser fingerprints etc). Then maybe experiment with hiding troll-posts from the other users, whilst displaying it to the troll, who thought they'd been ignored - etc etc. Or maybe auto-embed some very dodgy zero-sized images in their feed, if I know they were going through a company/university proxy.
After a while it just all got quiet and relatively happy, and it's been puttering along since 2003.
It's currently got over 9 Million posts, a load of marriages and children - and a few deaths with some 'best-of posts' for the departed.
I'm fully aware this isn't impressive as a potential unicorn, but I feel there's a bazillion other little sites, like mine, happily puttering along out there that are overlooked.