Seeing a lot of posts like this. Open source is wonderful in its way, but it's really not sustainable to work on projects that make money for other people - including big commercial interests - when they don't help out in any fashion. I'm not just talking money or contributions. I'm talking about simple acknowledgement: "we use project X" - even privately.
A open source library that I worked on at Intel (the Hyperscan high performance regular expression library) had to shed most of its staff (including all the original folks who worked on it, including me). One of the big contributing factors was a sense that "well, who really uses this". The answer was "tons of people, including some major Intel target customers" but a number of Hyperscan users picked up the library and never told anyone (not asking for public plaudits, but even a private communication would have been something to show our management).
When you can't even say "thank you, we're using your library now, it's great" in a goddamn email, don't be surprised when 75% of the people maintaining and advancing it don't have jobs anymore. Never mind paying money or contributing - even acknowledgement.
Open source is a recipe for burn-out. If something is important to people - especially corporate interests - there needs to be a way of getting paid. Much as I dislike those wacky "free for non-commercial use, otherwise, give me a call" licenses, I'm starting to see the point.