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.