Pratchett’s Samuel Vimes lays out the math in Men at Arms: good boots cost $50 and last a decade; cheap boots cost $10 and last a season. After ten years the cheap option has cost $70, replaced seven times. The boot wearer is poorer and still walking on failing boots.
The trap is not the price; it is the frame. “Frugal” almost always defaults to cheapest right now, which is a one-axis measurement on a two-axis problem. True cost spans time, replacement frequency, storage burden, and the cognitive load of repeatedly re-purchasing the same thing.
The source adds a quieter mechanism: review skew. People who spend more on an item review it more critically; people who spend less are more lenient. So the $30 sauté pan with 4.7 stars looks “better” than the $150 pan with 4.3 — but the rating gap is partly an artifact of expectation, not durability. The cheaper item’s reviews systematically overstate its quality.
The corrective is not “always buy expensive.” It is to ask the longer-horizon question before the receipt prints: what is this going to cost me by the time I’m done with it? Same as concentrated depth in work — the visible move is not always the move that compounds.