I know that a moon colony would be worth more than a visit to Mars.
Apparently, on my island, we're familiar with space program spinoffs.
We need a colony at L-5 first.
Why L-5? Too expensive to boost the parts there from Earth. Have to come from the moon. And since we're there mining anyway, why not build the colony there?
Plus:
Disadvantages
The risk of proton exposure from the solar wind as well as the health threat from cosmic rays is significant. In the Earth-Moon system, the orbit of colonies at L1 - L5 will take them outside of the protection of the Earth's magnetosphere for approximately two-thirds of the time (as occurs with the Moon).
A moon colony would most likely be under the surface and therefore well shielded.