If you have the time tona scratch your own itch and gift the results, it implies you have a source of income that gives you the time/lifestyle to do such a thing. You might be a tenured academic, or live in a society with a strong safety net. Or you might be able to do your day job in 1/2 the allotted time.
The problem is that a those scenarios are eroding precipitously, leaving more to seek compensation for their work output, whether it is closed or open source.
So what is really changing?
Higher education is less affordable and accessible to more families, and the value proposition is eroding. CS academics survive by joint ventures with corporations, not by their University salaries.
Escalating cost of living and reduction in institutional support systems push more people toward allocating their scarce spare time toward fundamental needs rather than contributing to the software commons.