You are right for $0.01 cost, but I wonder if that changes for $0.01 profit. What if your COCA (cost of customer acquisition) eats all but $0.01 of the revenue ? You are bringing in positive marginal revenue, and you don't have the downside you mentioned. Of course, you have others, such as this cost structure means you're making someone else rich, not yourself, and it's a very fragile situation, you can't absorb COCA increases.