Kinda hard for us to worry about this. By the time comes earth is dying and we need to switch planets, I think we will all be long dead. Not our fight to fight.
This is true. We are one asteroid hit away from going the way of the Tyrannosaurus and the triceratops. The short term gains in technology invention would also be very beneficial to us Earthbound humans. Could even replace war as driving our technology in the future.
Worth noting that several Muslim religious leaders have forbade living or visiting other planets, as it is an affront to Allah.
No terrorists on Mars! That could be a selling point to get rid of some really dumb people on this planet.