Hey HN,
I'm mostly a lurker on HN who's always super inspired by other people's small project that end-up making money. (Huge fan of Ben Stoke's Tiny Project [0])
After being burnt-out in big tech, I decided to write my own weightlifting app and set myself a humble goal of reaching $1000 in total proceeds. See [1] for my initial launch post.
I've now surpassed that goal and am now making about 500$/mo by selling premium features in the app. Android version is coming soon too. Doing the whole thing end-to-end (code, launch, marketing, support) was super gratifying and taught me a whole lot. I have to admit that I got almost teary eyed the first time someone bought one of my IAPs.
I'm not making a killing out of the app, and that was never the goal. But the personal satisfaction I got out of it was worth everything. I can't pretend to have derived any life lesson that applies to everybody from this, but this whole mini-journey was worth it for me, and I hope it will be for you too, should you embark in a similar one.