I feel your question subtly touches on one of the reasons people like open source and develop for it - there are many people who just enjoying doing their tech-nerdy things and giving it away for free. Before it was called Open Source it was Freeware, Public Domain and other words - the inherent desire to just do something and give it away for free is inherent in the nature of some folks, with no expectations on return (money, fame, etc.). Postcardware and Beerware were even a thing - "like my thing? send me a postcard from where you live" and I sent a bunch of postcards. :)