You could also say all it takes is a competitors to actually start competing. And by that I mean offering a better product and service, not also turning them into money printing "marketplaces" selling chinese crapware which is what they are doing instead, except without the remaining customer service guarantees that Amazon hasn't yet gotten rid off.
Or all it takes is regulatory agencies to wake up. After all, preventing the tragedy of the commons is their entire reason for existence. In fact, it's the only reason we give away a large chunk of our income in taxes.
I reckon in the first world, there is nothing that amazon sells that we can't simply skip or get somewhere else that would leave anybody in danger of death or serious injury.
I know it's tre chic to wallow in helplessness wrt certain things these days but we aren't yet completely without recourse even if we aren't going to buy our way into an entirely new order any time soon.