One big draw to Amazon is also their customer service. Especially with prime. If you order something it’ll be at your door in two days, and if it’s not Amazon will happily refund you and/or send a replacement. This is only possible because of Amazon’s massive infrastructure of shipping and fulfillment centers. This is why there haven’t been any true competitors to Amazon so far. You’d have to replicate not only their website experience (easy to do), but also their infrastructure (almost impossible to do).