How to find customers to talk to in the first place? i will not promote

Someone recently recommended me The Mom Test with some rules about talking to customers. I'm working on building a community for a new social app and trying to find the exact PMF, but i've been 6 months at it and I'm just as lost as day 1. The amount of cold outreach I've done is exhausting. Across various social channels, subreddits, facebook groups .... just getting a person to respond to me makes me question everything. Everyone says "Talk to customers". But hardly anyone explains how. "Go to where they hang out". Ok, done. Now what? I've tried so many different formats for cold outreach, or providing new posts on Reddit (although the moment they find out you're looking for customers it's blasphemy). I've slowly grown my actual user base to just over 500 in the course of those 6 months. None of them have helped me solve PMF. Everyone says to find some problem that people are having. I can't even get people to respond to a casual conversation, let alone discover any sort of denominator problem. So what the hell? Apps are saturated as is. It's not like people congregate in these hidden places and dump their common problems together just waiting for someone to build something. So i'm just not buying it. It's not as simple as talking to customers. Not for a social app at least.