How do you know the moon landing didn't transform civilization? Did you try living in an alternate timeline where it did not happen and find things to be the same?
What about all those scientists who learned to build rockets, who would later go on to help NASA launch the first weather satellites? What about the work done that led to the formation of the global positioning system? Are you sure it would have happened in the same timeframe by some other actors if NASA hadn't gone to the moon? Where would the scientists have gotten their training? What would have been the economic rationale for doing it?
Remember, too, that the moon landings were not scientific exploration. It was a military operation to prove supremacy. The russians put a man in space one month earlier, so Kennedy basically said "Yeah? you put a man in space? well we'll drop one on the Moon and then bring him back!"
It was an insane commitment to proving our supremacy. We sent fighter jet pilots on the first several missions, and didn't send a single scientist until several missions in.
Meanwhile, exploring the origins of comets helps us understand how the early solar system formed, which helps us understand how the universe formed, which helps us understand physics at a fundamental level, which helps us make better microchips, solar panels, and superconductors that make the tech in our world better at serving our needs.
It has nothing to do with "fun for those working on them", though I'm sure they have fun. Truck drivers probably have some fun too, but that doesn't mean delivering goods isn't worthwhile for legitimate economic reasons. Hard science is the same - it costs relatively little and the payoff, while abstract, is huge.
If you want to complain about spending, complain about military spending. In the US it is 70X NASA's budget, and 2x the military budget at the beginning of 2001. THAT is bloat. We know how to manufacture bombs. Making more doesn't do much for innovation. Funding science does.