Business model power

The mechanism

The business model decides where the profit actually comes from, and the strongest ones hold the obvious margin near zero so a quieter line becomes the engine. Costco is the clean case: it runs merchandise at about 12% gross margin against a roughly 25% retail norm, held down by an internal rule that no national brand gets marked up more than 14% without the CEO personally signing off. That discipline is why the roughly $4.8B in annual membership fees lands close to the company's entire operating income. The near-cost pricing is what makes the membership worth renewing in the first place, so the squeeze on one line is exactly what powers the other.

The tension

When the discipline is the moat, the model is fragile to its own temptation. Every quarter there is a rational-looking case to take a little more markup, and each time you take it you are charging against the trust that drives the renewals that are the real business. The model only survives while management keeps refusing the obvious win, so the design is the easy part; the hard part is holding the line for forty years while the easy margin sits in plain sight. A competitor can copy the structure; what they usually cannot copy is the willingness to leave the merchandise margin on the floor.