> Whether a moon base is needed or even beneficial is a question I have not heard a convincing answer in favor

If we want to go to Mars, the Moon is a good place to learn. Simple things like how to do trauma medicine in low g; how to accommodate a variety of human shapes, sizes and fitness levels; how to do in situ manufacturing; all the way to more-speculative science like how to gestate a mammal. These are easier to do on the Moon than Mars. And the data are more meaningful than simulating it in LEO. If we get ISRU going, doing it on the Moon should actually be cheaper.

If we don’t want to colonize space, the Moon is mostly a vanity mission. That said, the forcing function of developing semi-closed ecologies almost certainly has sustainability side effects on the ground.