> At some point in the future Earth will be uninhabitable for humans. At that point, it will make plenty of sense

Are you suggesting humans will damage the planet that much?

I find it difficult to imagine we can damage the Earth to such a degree that is is easier to try and settle Mars than undo the damage on Earth.

I want manned outposts on Mars as the next person. I like to think that the challenge of doing it is enough justification to undertake such an endeavour.