If you take the work involved in keeping a closed, armored, pressurized habitat viable on Mars and instead direct it to create a closed, armored, pressurized habitat viable underwater or underground on Earth, you should get the same insurance policy at a considerably lower cost.
not neceesarily, any event that was significant enough to wipe out the land based populationw oudl probably mess up the entire ecology of the planet, no reason being at the bottom of the ocean will save you.
