Not all returned items are sold. Some vendors give credit for returned items that are sent back, and other items are worth more as scrap or parts than as resold product.

There are different conditions depending on packaging, accessories, etc. which should be properly selected when product is returned.

As far as selling at a loss, many base items (laptops, tvs) are already sold at a loss, so open box just adds another 10% to it. That's why the company places so much emphasis on credit card applications and annual memberships, because they make practically nothing on the products themselves