alt Hacker NewsNASA does both manned and unmanned stuff. Don't conflate those when you are looking at returns.
Look at this joke of a list https://www.nasa.gov/missions/station/20-breakthroughs-from-... for an illustration. And those were the 20 best things they could come up with.
There are actually a lot of really interesting discoveries on that list. I haven't thought deeply about whether it represents value for money, but I would say that that is anything but "a joke of a list."