What defense budget the United States should have and what defense budget it can afford are separate questions. The debate raging in Washington about Pentagon spending ignores the distinction. Doves insist that we need a more modest military strategy because the current one is wasteful and economically unsustainable. Hawks say that the current approach is sensible and affordable. This article takes a third path, arguing that U.S. military policy is likely to remain extravagant because it is sustainable. We adopted our current strategy—which amounts to trying to run the world with the American military—because we could, not because it was wisest. Wealth and safety make the consequences of bad defense policy abstract for most U.S. taxpayers. So we buy defense like rich people shop, ignoring the balance of costs and benefits. We conflate ideological ambition with what is required for our safety. Unfortunately, the current political demand for austerity and fewer wars will only temporarily restrain our military spending and the ambitions it underwrites.