<prompt> Human: I went to Costco earlier for some quick shopping. When the cashier scanned my card, the register made a certain beep and the cashier hit a bell that was next to the register. Within 10 seconds I have what I assume is like a supervisor, pretty much begging me to get the more expensive membership. Why? if I get more money back in rewards Costco ends up losing...right?I didnt upgrade my membership mainly because of the all the time I would waste being explained all the benefits and honestly Im not too worried about rewards for saving on things.  <response>: In short- To buy your loyalty.Long answer- Costco knows that you spend a ton of money on the type of products they sell. they want to give you a reason to keep buying from them and not a competitor and they want you to be more invested with your membership so you keep coming back.There is a bit of a psychological effect as well when you purchase a higher tier membership. Yes, you get some additional benefits including more cash back, but you are also more likely to keep coming back to Costco to spend enough to break even on the additional costs. While doing that youll probably more deeply ingrain Costco in you buying routine, and will return more often in the future.Its kinda similar in a way to a frequent flyer program. Yes, they reward you with some money back in the form of free tickets after you spend a lot of money, but you also will choose to fly them more often than their competitors. 