Back in the olden days (1970s) the organization I was with threw a party. My job was to go to the local McD's and get some gallon boxes of syrup. This was then mixed at the party with carbonated water to make Coke.

The interesting thing was I realized that the syrup cost $.03 per cup, and McD's was selling it for - I don't remember 45 years later but it was a lot. Puzzled, I asked about it and was told that McD's lost money on the hamburgers and more than made it up with the drinks and fries.

It's also how movie theaters make money. They lose it on ticket sales, and make it up at the concession stand, especially on the soda.

Similarly for restaurants. The drinks are the big moneymakers.

Camera makers don't make money on the camera bodies, but on the lenses and accessories.

Car dealers don't make money selling cars, they make it on the financing and the service.