A green cheese factory?

Space exploration is in the news again as a result of the deliberate crashing into the moon of a space probe that had ended its useful life - in an attempt to establish a better understanding of the moon's composition. This, one report suggested, might help in the eventual construction of a manned colony on the moon. What on earth for? Why would we want to spend billions of pounds (or dollars more like) on such a project? It's not as if we haven't got better things to spend that sort of money on. There was perhaps some dubious merit in the original race to the moon - back in the days when the US and USSR were playing the "my rocket's bigger than your rocket" game, and the moon was simply a prize to be gained and displayed in your trophy cabinet. But those days are gone, thank goodness, and with them that sort of reasoning. So any future attempt to put a man on the moon has I think to be looked at on a cost-benefit basis. We know the cost will be enormous, so will someone please explain what the benefits will be?