"Dr. Teller told me that he thought that the best resource the moon had was space. I thought that was a smart aleck answer, but he went on to say it was space where you could pretty much do as you liked. In short the moon doesn't have an EPA or any other regulatory agencies - or any lawyers."
http://www.spaceref.com/news/viewnews.html?id=1119

When I was a kid- say somewhere around 12 or so. I began thinking that stock market was a huge waste of money [wealth/human effort/time] and held this idea for a while, but after years to decades I learned that this idea was completely false. I now know that there is no known system which more efficent than the stock market- that the stock market is a huge wealth generator- it not only prints money like goverments, but it makes money/wealth- unlike governments. The stock market has made all the difference in the same scale as saying democracy or technology has made all the difference. It's critical, vital and/or an essential aspect of democracy or having a prosperous enlightened nation. Now, as a kid wasn't wrong in the sense that the stock market is wasteful- any fool can see that- but it's similar to democracy in that we simply don't know of a better system. A stock market can "make mistakes", and it can be and will be corrupt to some degree- though in a sense the "good news" is that too much corruption kills it, though this isn't good news because this results in general poverty. I don't want to belabor this, so in a word the main thing "good" about stock market is it "allows" people to do things, but more specifically it allows people to do new or different things. Without this element, stock markets have no value. The same can said about science or democracy. So this word is Freedom.
Of course freedom isn't wild and crazy. Freedom starts with being "allowed" to think, then "allowed" to say, then "allowed" to do. Freedom can be measured by awareness to problems or possiblities, the organization needed to do something, and changing conditions/realities/fulfilling dreams.

So, the Moon, and Mars and everything else is a clean slate. In order to realize this value, humans must be able to go there- or at least in some way to interact in a significant manner with these environments. And the value to Earthlings is not solely to allow some people to go somewhere so these people can enjoy themselves- but that these spacefaring people will change conditions on Earth. And what this costs Earthlings should be insignificant in terms of what they could get back in terms of the "investment".