This is not true for bitcoin for instance where it all started from a forum. How would one know that something is happening in a forum ?
Trying to find the next bitcoin like thing will probably be frustrating.
You are looking for things that other people laugh at or dismiss but in your mind will win.
Something like Elm programming language (or its paradigm at least) But you don’t get rich but getting Elm early like Bitcoin :)
Newton did theology, alchemy, calculus. All of these were/are considered crazy ideas, but one worked.
It follows the same rules. Reddit, HN, much of that stuff won't attract people doing big things.
For example, my friend just built a platform with $250k GMV in 3 months. It started with a few back and forth comments on Facebook, and later an invite-only Facebook group. I've seen Minecraft and Dwarf Fortress back when they pointless experiments. Both were popular on forums.
There's a lot of things going around, but it's easy to get sucked into the wrong forums and communities and spend all your time and energy there.