A study of economics usually reveals that the best time to buy anything is last year.

The joke compresses a common economic experience—price increases over time—into a paradoxical “lesson” from studying economics: the optimal purchase moment is always in the past. It satirizes hindsight bias and the frustration consumers feel when inflation (or simply rising costs) makes yesterday’s prices look like bargains. The line also plays on the gap between economic theory and everyday life: instead of offering actionable guidance, “economics” seems to confirm what people already suspect after watching prices climb. Its humor comes from treating an impractical conclusion as if it were a serious analytical finding.