I took a sabbatical from work in 2017 and devoted that time to creating an open source project which I felt was important to exist in the world. I am not wealthy, nor was anyone else supporting me; I had saved up enough to take a year off, and instead of travelling or learning the saxophone, I spent my time developing software that I released under GPL.

I guess because I was not living hand-to-mouth, I didn't "need" the money? But I wound up nearly going into debt, because it took another year to get a job after that--turns out that maintaining an open-source project is not an asset for employers but a liability. I had an offer from a HugeCo for decent money, but I turned it down because it would basically have precluded me from working further on this project which is only now starting to walk on its own.

It's not my entire working life, by any stretch, but those 2 years were 5% of it, and I figure that cost me $200k+ in "lost" wages. And that does not count all the "free" time I've spent since, fixing bugs and helping people use it, because I love the thing and I want other people to love it too. I'm glad I created it, it's very useful to me and other people who do data exploration in the terminal, but now I have to accept that I probably won't ever recover any significant amount of that value, because...people don't pay for open-source software.