system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some stores such as Sam's club and Costco charge a membership fee just to shop there?
gpt
Costco products are essentially sold at cost-price. The profit comes almost entirely from membership fees.

Sam's Club operates on a slightly different model, but the outcome is the same. The main difference is that Sam's Club is a "warehouse store" for Wal-Mart, so Sam's Club stores are the hubs with Wal-Mart stores as spokes. They can sell things at Sam's Club, and if they don't sell there, they can be broken from bulk and sold individually at Wal-Mart.