Some other commenters in this thread have pointed out that nobody is forcing open source developers to work on the contributions that they make, and that is strictly speaking true. But in the culture of software development, there does seem to be an ambient message often repeated or hinted at, that it is good to "give back" to open source by contributing and that it is virtuous to do so. I now am starting to rethink…
Is there research comparing the current situation with a hypothetical world where OSS doesn't exist? How many less developers would have a job? How much less would the remaining be paid? I'm imagining it and that's not a world I want to be in.
To add a bit more to the "factualness" of the conversation, according to the Bureau of Labor Statistics Software Engineers in the U.S. took home $144 billion, which for comparison is more than the revenue of Alphabet or Microsoft. How much of that do you think can be attributed to OSS?