Amazon loses money on every sale, yet somehow they are far pricier than ebay (which is profitable), and that is far pricier than aliexpress.

A quick sample of like-for-like products shows that typical sale+delivery price on amazon is 30% more than aliexpress and 18% more than ebay.

I really don't see how you can charge 30% more than a profit making competitor, sell in larger volume, yet make a loss.