I guess I just vehemently disagree. Nearly all of the early open-source software that made the internet possible was produced in universities. The only reason it was sustainable was because it was professors being paid by the university, or students doing it for free. Implying that means it's viable for all these other projects that were created and maintained outside of a university setting is just not accurate. There's also this fallacy of: it worked this long so it will continue working forever.
For me the long and short of it is: the only way I can foresee open source working in the way the purists want is if there is a universal basic income. SOMEONE has to pay the bills, and as we've seen time and again, hoping to feed your family on donations is a fool's errand. With UBI, artists of all kinds (including developers) can pursue things that would otherwise be impossible. Without it, we're left with the constant push and pull of people either burning out maintaining stuff in their spare time, or hoping a given corporate maintainer wants the same features and functionality as the community.