"Sunk cost fallacy" is one of the most damaging mental tricks for money decisions: people stick with bad purchases because they've already spent time or money rather than because it's the best current choice. It's common with subscription bundles or hobby gear bought for a "one-time" enthusiasm that fizzles. Recognizing sunk cost thinking helps you cut losses sooner. Practical rules: decide on keeper criteria before buying, set short evaluation windows, and treat sunk costs as sunk — not a reason to continue. This question checks your ability to identify sunk-cost behavior.