Sure simply learning this stuff is interesting, but the costs are so extreme it’s effectively a vanity project.
The traditional example is doing basic physics that needs long duration microgravity.
These sorts of research aren't a large fraction of what's currently done on the ISS, but it's also not zero.
1: https://en.wikipedia.org/wiki/ZBLAN
2: https://www.asme.org/topics-resources/content/growing-human-...
Aka Manufacturing would be that larger goal I was referencing.
That said, when you get a massive subsidy by NASA, these costs are less obvious.
But even beyond that this is precisely what governments are supposed to do, gather and distribute costs that would make little sense for individual companies or even massive conglomerates to do.
Even beyond things like that the only real way to study the effect of space on the human body is to put people up there for a long time and test. There are some analogues available here on Earth but they can only really test a few things at once like fluid redistribution and not the entire set of effects.
https://jacobsschool.ucsd.edu/news/news_releases/release.sfe...
The data points from microgravity experiments don't exist in isolation; presumably there are data points for similar experiments at surface gravity. Removing gravity from a system could say very much about how gravity affects the system, and thus how the system works on Earth.
We also might discover effects so important that it would be worth going to microgravity to get them. Stepping out into the unknown just to learn how it works is important.
(Disclaimer: I know jack about what kind of microgravity experiments are going on.)