The only scientists who can afford to work for free would have to be independently wealthy, that's not very common. I don't think there is anything wrong with charging money for work, even if you do enjoy that work. Like any kind of work, research science has its share of 9-to-5ers who don't really care, but those people have their uses, too.

> It's the ones who are always whining about how they need constant boatloads of public funding (which is supposed to be spent on public services)

The core problem is really that often public money spent on science leads to results that are privately monetized and closed off from the public who funded it. That's why I believe SciHub is such an important institution, because it makes research results accessible to the public who funded them in the first place. However, funding for space-based data gathering (such as telescopes) has generally led to publicly-available data - the same cannot be said for, say, biomedical research.

I would argue that research is a public service, as long as it doesn't get immediately spun off into patent-encumbered "university-adjacent" enterprise (which I would argue is nothing less than legalized corruption). Of course the issue becomes: how do you prioritize science funding and how do you balance it against other public services?