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

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.