Because Gregg Easterbrook can't figure it out.
Top Ten Reasons to Go Back to the Moon:
10. “To [re]organize and [re]measure the best of our energies and skills.”
9. To stay technologically ahead of other nations that have active plans to go to the Moon, particularly those who do not recognize basic human rights.
8. To conduct scientific research, in order to understand how the Moon was created.
7. To determine if water ice and other volatiles exist in permanently shadowed craters, not only for the potential use of these resources, but also to better understand fundamental physical and geological processes (cold-trap volatile migration, volatile flux due to meteoroid and comet impacts) of which we have limited understanding.
6. To convert lunar silicates into solar cells for Solar Power Satellites, in order to provide clean, safe, and cheap energy for Earth (mid-term).
5. To use the Moon’s relatively high abundance of helium-3, in order to provide clean, safe, and cheap energy for Earth (long-term).
4. To learn how to make things on another planet.
3. To learn how to live on another planet.
2. To preserve the human species, should the Earth ever be destroyed.
1. "Because it is there."
I could elaborate, or keep going with other resons. I will try to respond to any comments.