SpaceX priced its IPO at $135 per share, raising $75 billion and valuing the company at $1.8 trillion. The financial press will spend the next several weeks arguing about whether that number is justified by Starlink’s margins, the Starship program’s trajectory, and the AI infrastructure buildout. Those are reasonable conversations to have. But they are also, in the deepest sense, beside the point. The more important question is not whether SpaceX is worth $1.8 trillion to investors. It is whether the mission that animates the company—a self-sustaining, multiplanetary human civilization—is worth pursuing at all. The answer is unambiguously yes.

Begin with a fact that tends to get lost in debates about climate change: Well over 99 percent of all species that have ever lived on Earth have gone extinct. Five mass extinction events have swept the slate almost clean, and not one of them required human assistance.

The Ordovician-Silurian event 444 million years ago was driven by glaciation, or vast ice sheets that caused sea levels to drop sharply, destroying shallow ocean habitats. The Late Devonian crisis followed as expanding land plants led to oxygen-depleted waters and global cooling. The Permian-Triassic extinction 252 million years ago resulted from massive Siberian volcanic eruptions that released huge amounts of greenhouse gases, causing extreme warming and ocean acidification. Triassic-Jurassic volcanism raised CO₂ levels and destabilized climates. The Cretaceous-Paleogene extinction 66 million years ago combined an asteroid strike with volcanic activity, creating global darkness, acid rain, and cooling that ended the dinosaurs.

There is no reason to think that naturally occurring challenges to human survival are a thing of the past. A super volcano eruption beneath Yellowstone could inject enough sulfur dioxide into the atmosphere to trigger a volcanic winter, destroying global agriculture. A sufficiently large asteroid strike of the kind that ended the Cretaceous would produce an “impact winter” of similar character. A supernova within 30 light-years of Earth could strip away the ozone layer, exposing all life to lethal ultraviolet radiation. The sun itself will eventually boil the oceans away as it evolves into a red giant.

Just because Earth is habitable today does not mean it will be habitable tomorrow. Our planet is not a sanctuary. It is a rock in an indifferent cosmos, subject to forces against which a single-planet civilization has essentially no defense. The only meaningful hedge against that exposure is to become two civilizations, then several, spread across worlds that no single asteroid, no single super volcano, no single dying star can simultaneously destroy.

That is what the $75 billion raised today is ultimately for. Not Starlink subscriptions, though those matter. Not launch contracts, though those matter too. The deeper logic of SpaceX—the reason Musk has described Mars colonization as a life insurance policy for the human species—is that technological and economic progress must eventually escape the gravitational pull of a single planet.