You are correct, but note that one very key edge that Amazon used to as a competitive edge is no longer available to new entrants in the business. For the first 15 to 20 years of Amazon, they were able to be cheaper than their competitors due to the fact that sales tax only had to be collected in states where they had a nexus.

This gave them a pricing advantage which drove more customers to them which they intelligently plowed back into the business in building out their own network, no small feat of course.

A newer competitor would no longer have access to that simple sales tax advantage, and so would have to find something else to compel customers with. Barring that, Amazon/Walmart/Costco/Target/Home Depot/Lowes/Best Buy are tough to compete with because they already offer rock bottom pricing and they don’t have to invest in a ton of new infrastructure for logistics.