It was $5 cheaper than regular menu price. But he ordered a literal 100 times a year with the coupon, tipped the delivery driver $5 every time and the order still was more profitable than $15 of chicken wings.

Once the coupon left, he went to the competition. I used to spend about $1,000 a month in advertising just to get a few new customers to call. Keeping the ones you have is orders of magnitude cheaper, even if they complain about "cold pizza" once a month or so to get a free pie.