Re: " You build underground. "
I suppose the question is, do probabilities stack like that? If we keep adding the probability of a location suffering an extinction event (natural, human, disease, economic etc), does it decrease as we add more locations, or just keep the average?
"The fact that you have such a fantastically poor understanding of science that you A) think we should live on the surface of a planet in a big gravity well as a colony world and B) think that a colony is particularly hard (as opposed to merely outrageously expensive) means you shouldn't be allowed to have this conversation at all."
A) Please support this argument with an understanding of biology and it's dependencies. Using robotics to collect materials is a great boon to us in low G, using humans increases a risks in total.
B) Getting to space is hard. It's not just expensive. It's brute force effort. It's expensive not in just monetary terms, but in time and resources (both physical power/energy/materials and time/research/planning). We can pull it off, but again, it's diverted resources that take excessive time-scales for a return investment. That increases risks, not reduces them. It may pay off, but it's a gamble, not an "insurance", unless we have the surplus for it.
We have proof of A) in our current space exploration. We have proof of B) in the calculated return times for our nearest star (or Mars if you wish, it's still resting at 6 months 1 way trip at best theoretical transit times).
Science is not a failing here, mine or others, but feel free to expand on the ideas and how it might work in the future.
Biting the hand that feeds IT
