The real "how" is in the last section: Amazon pushes up prices by being so big that people feel they have to sell there. That is the root of the issue and the place to solve it, by destroying Amazon and breaking it up into small pieces.

In my view all of the conveniences that people are referencing in the comments (e.g., easy returns) are also consequences of that, and they are also bad, in the same way that it is more convenient to eat a bag of potato chips than it is to cook a meal, but the potato chips are worse for you. The convenience derived from large market share (Amazon's or any other similar excessively large market player) is not worth the downsides. We need to rip the band-aid off and accept that less convenience is better.