this might be true for products where costco was offering a much better price, but I'm sure there were also plenty of annoyed customers who just bought the item

this might be true for products where costco was offering a much better price, but I'm sure there were also plenty of annoyed customers who just bought the item somewhere else for a slightly lower discount. presumably there is some way of approximating this ratio and using it to adjust these kinds of loss estimates. I guess lovethesales.com might choose not to adjust the figures in order to report a juicier story.