do people with masters or PhD STEM degrees make much more than people that only have bachelors in similar fields? I thought that the gain was fairly small. Even in the same area, I know a literal rocket scientist working as a rocket scientist with a masters degrees from MIT who makes less than your average programmer/sysadmin.

As far as I can tell, once you make programmer, having a bachelors vs. a masters doesn't seem to make much difference. (Once you have the job, lacking even the bachelors doesn't seem to make much difference; but those of us who have the job with out the degree are relatively rare, which to me points at the degree helping you to get the job, even if it doesn't change your pay all that much once you have it.)