I agree 100%.
My ethics now (different than in my youth) preclude me from taking money and giving no product or service in exchange. To me that is no different than a scam or theft. I see this as a financial transaction first, an emotional one second. Feelings of competition, contempt, anger at being manipulated, a desire to get revenge on a guest who tried to outsmart me are all negative emotions that I find exact a cost far greater than the monetary one.
Other people take a different path and are perfectly happy to do so.