Not the person you are replying to. I live near a Costco and it offers good value for money. I go there multiple times per week. I use their pharmacy which is very reasonable even without insurance. I buy fresh produce and eggs and milk and salmon. I get my tires rotated and balanced there. I also get my eyeglasses made there. Their food court is also something I can’t pass up.

Costco sells fresh food (produce, meats, baked goods) and quite a bit of prepared-on-site ready-to-eat deli choices (soups, salads, tacos, etc...).

While sold in larger packages, they don't last any longer and so must be bought frequently.

From families I know: food is the reason. Athletic teenagers consume a lot of calories. Proteins, fruits, and vegetables along with milk, eggs, cheeses and snacks are easy to buy in bulk at Costco. These items are replenished weekly.