⚠ A Second Source, by DesignModerate threat

The most reliable threat to a dominant launcher is not a better rocket but a customer determined not to depend on it. The Pentagon splits its launch awards deliberately to keep rivals alive; NASA nurtures competitors for the same reason; and commercial giants building their own constellations — Amazon foremost among them — have every incentive to avoid handing their launch dollars to a company whose Starlink competes directly with them. Dominance this complete generates its own antibodies: the biggest buyers of launch are actively underwriting the alternatives, precisely because SpaceX has become too important to leave unchallenged. The moat is wide, but the field is filling with well-funded entrants whose motive is strategic independence, not profit — Amazon has committed over $10B to Kuiper alone¹ — the hardest kind of competitor to out-wait.