The pressure range range between vacuum, mars atmosphere and earth atmosphere is 10⁵Pa. The pressure at the bottom of the ocean is 10⁸Pa. Humans can survive the former with little more than strong tensile garment and a breathing apparatus, the latter requires massive, crumple-resistant pressure vessels around everything.
Finally someone with the sense to realize what difference an order of magnitude can make to a decision. Now lets compute how likely we are to die by an asteroid vs how likely we are to die being stranded on a barren, frozen rock 60M Km away from the nearest source of critical supplies.
That depends on your time horizon. Probabilities of catastrophic events tend towards 1.0 individually. But within the same time horizon you can keep it close to 0 with sufficient redundancy and recovery.
So the tradeoff would be risking a finite amount of human lives in the short term to reduce the risk of a total loss in the long term. I.e. over time it becomes fixed vs. fractional cost.
