Had a look at the closest moon to me - a fairly small one - and even if it was just one part per million were useful, it’d still come out at 7.35e13 kg of usable material. That’s a LOT of zeroes. This is the absolute lowest end of estimates I’m willing to make as the more likely amount of useful material extracted would probably be one if not several orders of magnitude greater.
We’re talking billions of tons of usable material on that low end estimate. On a relatively small moon at that.
I haven’t checked what the average amount of moons per system in New Eden is, but there’s roughly five thousand systems in New Eden and as I understand it roughly half that in w-space. A very very lowball estimate of moon averages translates to an extremely conservative forty thousand moons. Now remove all that are tied to inhabited planets in order to avoid tidal issues etc and you’d still probably sit comfortable with the majority of these.
Another set of zeroes to add to our number then.
The tl;dr here is basically that we can churn through moons as fast as we possibly can and it’d still be like the proverbial bird sharpening its beak on a mountain once a day, then wondering how long it’d take to turn the mountain into dust.