I always told myself it wasn't worth the trouble to apply to jobs where the salary was 50%+ higher than my current salary. When I finally did (because the requirements were so well aligned with my skillset), I was floored by how eager they were to interview me. I think my previous job paid around 75k CAD which is... Admittedly terrible for someone with my experience. Now if I apply to jobs offering twice that salary I can often get an interview.
I know these numbers are tiny for many people on HN, but bear with me.
It truly does pay to just try. Why not find out? I've probably worked for far less than I was worth for the majority of my career. The day I became a developer I was titled as a graphic designer (I was a designer who could code), and I kept that title and salary for 2 years. That really set the tone for me, I think. I was making $32.5K/year building honest to gosh web applications.
Ironically I decided to do my own thing once I realized I was undervaluing myself. Probably not wise, but I've wanted to for so long and I never did because I figured I didn't have the skills.