Re: One minor problem...
It's an interesting one, certainly.
Investors pile into profitless stocks when they see a possible monopoly on the horizon, so relentless growth is key as is the appearance of increasing clout.
Amazon have both of those in spades, with AWS being a relatively small part of a giant empire which is much less contestable. Large parts of the ecommerce landscape now more or less belong to them, and their clout is sucking the profitability out of downstream businesses like publishing. If they chose, or were forced by investors, to stop investing in growth and focus on making and distributing profits then they could likely make profits to justify their share price.
With AWS I'm not so sure. Google and Microsoft aren't going to go away, and the enterprise software vendors won't either. Plus the market feels almost infinitely contestable and so new competitors are likely to spring up constantly. If Amazon can turn IaaS into a software play and keep investing furiously into it, they may have a sticky and therefore profitable market. Otherwise turning the market on its head, though painful for their competitors, may not prove as profitable for them as their shareholders would like.
The other important consideration is anti-trust. If they keep their profitless growth up to the point where their monopoly power attracts the ire of regulators then their shareholders may not get the best out of the scale they've reached. I'd say they're on the verge of that in the book market.
If I were an investor I'd be highly enthusiastic about their performance to the present but keen to find out how they plan to monetise it.