This isn't about moving everyone to Mars. This is about colonization, which always happens with an extremely small fraction of the original population.
I'm not negating that proposition. I am saying that people have alternatives in life and I can't imagine a life on Earth that is so bad that moving somewhere that has no water, no atmosphere, no food, no anything would be better.
Chance of dying -- high. Chance of having children -- low. This is not rocket science, as they say.
Not many people become polar explorers either. For some people the challenge is worth almost any risk, look at nutters like the wingsuit proximity flyers, for instance. If there is a rocket to Mars you will have no problem filling it. For certain people you will have problems sending them away. I suspect a team of people may have to physically restrain Brian Blessed from invading the launch site to try and stow away on board if he isn't among those selected.
