Costco has a sizeable customer overlap with Amazon, especially among wealthier shoppers. It's a looming danger for Costco if those shoppers decide they don't want to pay for both. But the company has defended against its competitor through low prices, offering fresh food and gas, and creating a treasure hunt buying experience that can't be copied online.
Money.cnn.com reports how members pony up for the subscription because they believe they can make it back over the year by buying cheap stuff in bulk, like giant jugs of ketchup and mayonnaise. Costco's 93 million members are exceedingly loyal: As of June, Costco reported 90% of its members renew their subscriptions.
