You are using words like 'rational', 'dispassionate' and 'coherence' when what we are talking about with empathy is adding information with which to make the decision. Not breaking fundamental logic. In essence are you arguing that a person should never consider anyone else at all?
I believe the proposed budget is being marked up tomorrow (July 15th, 12:00). Currently the NSF budget is set to be ~$7 billion, a 23% cut compared to FY2025. I'm not sure how this affects LIGO exactly.
I see what you're saying and agree that we probably would have noticed the discrepancies in GPS positioning pretty quickly if we had tried to make it work without knowing about general relativity (GR). But it took _Einstein_ the better part of a decade to develop GR. Even if he hadn't existed, GR still would have had to be discovered by scientists using public funding. What company would pay someone to work on this problem for 10 years without a guarantee of success?
I also don't think there is a strong correlation between studying things close-by, e.g. in our solar system, and how useful the finding will be. Our next break through in particle physics may come from studying dark matter, black holes or quasars. Maybe that will help us build even better computers? Or faster than light communication? We don't know where the treasure is buried!
It's worth keeping in mind that the budget for scientific funding in developed nations is typically ~1-2% of the total budget. Most of that money usually goes to medical research (as it should), which directly improves the quality of life for millions of people. The remainder goes into R&D which drives progress, yielding benefits across many different industries. Slashing the science budget and investing that money in homelessness instead would probably not fix homelessness in HCOL areas (issues are structural) and would end up being a major net negative for the rest of society.
Most of the benefits of blue(dark?)-sky research are unpredictable almost by definition. We're exploring for the sake of finding answers about the universe, and in the process learning 'unknown unknowns' which may pay off later. Using your example - quantum mechanics wasn't invented with computer chips in mind.
Having said that I think that there are some practical benefits coming from this research that aren't commonly discussed. For example: adaptive optics - which is heavily used in astronomy - is also used in medical imaging and national defense. Astronomers also drive a lot of detector development. Previously this was the CCD, now things are moving into new, exotic devices like MKIDs. Maybe one of these new detectors will end up in a mobile phone camera in the future, and you'll be able to take excellent photos in low-light levels. There are many more examples I'm sure, but this is just what I have off the top of my head..
The final practical AND philosophical application I can think of, is that we are about 10-20 years away from putting direct constraints on life in the universe. A big proportion of astronomers are currently working on this. I think an answer to this question will dramatically change how society views itself.