OK, you just seemed to be saying that those things were better because they could support themselves financially.

I don't think they're on the same order of magnitude in terms of knowledge gained - those are mature industries, space travel isn't anywhere near, so the gains should be much more dramatic and broadly applicable.

No, the main thing is that self-sustaining enterprises aren't up for public debate, so there's no reason anyone would criticize them as frivolous. Whereas anything that needs public funding, like space travel historically has, is automatically subject to a debate about its worthiness.

Sure there is - I know people who would call those things frivolous. Football consumes a serious outlay of energy for comparatively little lasting benefit. It's not scrutinized as often as things that are funded with taxes, but that doesn't save it from frivolity. Anyway, we're probably arguing past each other. I see taxpayer funded science of all sorts as being more worthy than most things, because I view scientific discovery as the foundation of the country's economic competitiveness. Most things seem frivolous by comparison.

But doesn't most economic production and most scientific discovery ultimately serve frivolous ends anyway?

Maybe, but some of it helps ensure the continued survival of the species, which is about the least frivolous thing possible.