[Theophilus]

If the Moon were made of gold {or name your exotic element/material: platinum, plutonium, diamonds...}, it would not be worth the cost of traveling to get to it. The Moon, Mars, the Asteroids, The Galilean Satellites are all rocks - nothing but rocks. Columbus did not sail to a new world made of nothing but rock, containing nothing but rock, across a desert ocean of acid, poison, lava, withering radiation, insanely hot magnetic belts and not to mention a freakish vacuum in massive ships made of gold paddled tediously with oars of diamonds the size of popsicle sticks.

[eclectic]

The Moon, Mars, the Asteroids, The Galilean Satellites are all rocks - nothing but rocks

What about Uranus? You seem to have all the answers. No need to go to Space indeed, just ask you

[Cincinatus]

Your mind is rooted in the 17th century. The principal "commodity" of a knowledge society is knowledge -- not gold, not platinum, not oil, and not precious gems. And exploration of unknown worlds produces new knowledge. It'll pay off, somehow and someway. And in amounts undreamed of by the greediest of Conquistadores.