The odds of extinction within the next 50 years are still low. A self-sufficient Moon colony would cover most of the disaster scenarios adequately while being a lot cheaper to build than a Mars colony. Besides, having a self-sufficient lunar colony would probably make building a Mars colony much cheaper.
On the Moon, solar energy is abundant (close to the Sun, no atmosphere) and so are the metals used in spacecraft construction. Without atmosphere and with a low gravity, launching cargo to Mars is easier and can be done with a magnetic rail launcher, effectively using solar power to launch a spacecraft to Mars.
So, I'm not that guy, and really trying not to be that guy, but wouldn't it be fair to summarize your general point as: "That's no moon. It's a space station." ? (mainly mentioning it because it could be taken for an inspirational saying in this context)
On the Moon, solar energy is abundant (close to the Sun, no atmosphere) and so are the metals used in spacecraft construction. Without atmosphere and with a low gravity, launching cargo to Mars is easier and can be done with a magnetic rail launcher, effectively using solar power to launch a spacecraft to Mars.
I's even greener to go for the Moon first ;-)