Remember that AZ takes a percentage cut of each sale and is also able to ship cheaper than basically anyone because of their position in the market. So imagine you have a product, and in order to make a profit from said product you have to charge $x. But in order to profit after Amazon’s fees you have to charge $x + $y on Amazon’s platform. So that’s where the “prices too high” cones from. If your product does well on amazon they’ll make their own version and sell it for less than $x. Now you get less sales on AZ and you can’t go back to selling on your own site because you can’t compete with your higher shipping costs, plus AZ can run at a loss on the product they copied from you until you’re out of business… This is where the “prices too low” comes from; the price AZ can offer is too low for you to compete with. After you go out of business, AZ can charge whatever they want. So you see “prices too high” again.
When you start selling a new product you take on risk because there might not be a sustainable market for it. AZ never has to take this risk, but they can reap the rewards from your risk if it does well.