[BobaFloutist]

How will it save lives? It'll maybe create more lives that persist beyond those on Earth, but I don't think it will meaningfully lower our global population, so a planetary catastrophe would still kill just as many people.

Also "the most important thing?"

You don't think there's any lower hanging fruit on-planet we could attend to first? Maybe addressing hunger, poverty, pollution, resource wars? You think getting the first ten-thousand people to Mars is a bigger priority than eradicating diseases that kill 10 times that many annually and that we have all the tools necessary to control? Really really?