If I'm dismissive it's because we've had a lot of
field tests of socialism throughout history, as well as in economic studies, and the results are always poor. It's a dangerous mindset to not examine critically because it is a slippery slope towards communism, the most inhumane type of society responsible for the most deaths in human history (much more than religion).
> Value in society is created by teachers, whom get paid poorly.
Many teachers (pre-college) are essentially babysitters who recite state-certified textbooks. This not value in itself, but it does free the parents to work to create value. Value is also created by the students who go on to create exceptional things. Some are inspired by good teachers, yes, but this seems to be the exception than the norm.
> By PhD students, who get paid poorly.
Apprentices in older times got paid poorly too, but many went on to create value who wouldn't have otherwise without the extensive training. It's an investment. You don't get paid well while in training because you're still an unknown quantity for the most part.
> By parents who raise their children well for no compensation at all.
The purpose of capturing value is to be able to start a family and pass on your genetics (for most people). And those who raise their children well often do get compensated later in life, if not with direct support, than with higher probabilities that their children will be successful and continue passing on their shared genes.
> By all the millions of people who get to work every day and don't get compensated handsomely for the effort.
You don't get compensted for effort, you get compensated for value. You can dig a ditch with a spoon for a lot of effort, guess what, it's not valuable.
> If there are so many people willing to work hard and sacrifice for the good of society without any chance of striking it rich, why should business owners be the exception? That's the fundamental question socialists ask.
As I showed above, hard work a.k.a effort is not, and should not, be a determining factor of one's wealth. Many people work hard but are using "spoons" so to speak. This doesn't create value. Planning the logistics of a digging operation (tool equipment rental, worker recruiting and scheduling, end customer sales, planning real estate builds, etc) creates value, even if it means I only plan these things for a few months then sit back while other people do the digging.
Now not everyone can do that simultaneously. For one, not everyone is smart enough to do higher-level planning. Intelligence is rewarded economically, and we see this with IQ-income correlations. Secondly, even if everyone were the same intelligence level, we can't have everyone be a planner/developer and nobody be a digger (or excavator operator). But then guess what happens, the worker class becomes rare and so the free market will start paying it much better as demand increases. If physical labour becomes scarce, that's what gets paid more.
Because we can fight neither the reality of scarcity driving value, nor the reality of greedy human nature, we ought to design systems whereby these forces can be put towards good. That's what capitalism does, and there's many examples of everyone being better off as a result (e.g. 600M+ Chinese people eating a lot better in the last few decades).
Finally, to emphasize human nature again, none of the examples you listed are exclusively for the "good of society". Being a teacher is a job with decent pay and good vacation, being a PhD student is an investment towards your future (earnings), being a parent and raising children well is how you pass on and secure your genetic lineage, and work is for economic survival, and eventually gives one the power to pass on their genes.