Whether or not Amazon has a monopoly doesn't change the strategy...

Whether or not Amazon has a monopoly doesn't change the strategy & not all monopolies have to be defined by some arbitrary percentage of market share.

Amazon is pioneering anew strategy whereby they sell without any need to make a profit thereby forcing their competitors to head down the same path in the hope of surviving.

Difficult for a business which requires a profit to survive & compete with a competitor who has no need for margin because they are prepared to operate with a view to building marketshare at all costs.

As Beezos says "your margin is my opportunity"

Of course as Amazon's competitors die off as a result of war they can't win Amazon may eventually meet some sort of definition as a monopoly in some jurisdiction/s but by then the war's over & their competitors dead.