An Amazon employee from 1997-2004, Eugene Wei spells things out for people who still parrot out the lazy argument around Amazon’s profitless business model:

Amazon has seen that lowering its shipping costs and increasing the speed of shipping items to customers is like a shot of adrenaline to customer’s propensity to buy from them, and so it has doubled down on building more and more fulfillment centers around the world. When I joined Amazon it had one fulfillment center. Today it has dozens just in the US alone, and I would not be surprised if it has more than 100 fulfillment centers worldwide now.

That is a gargantuan investment, billions of dollars worth, and it takes a significant bite out of Amazon’s free cash flow. Add in its investments in infrastructure to support a growing AWS client base, and Amazon has again hiked its fixed cost base to a higher plateau. But for Amazon this is nothing new, it’s just the same typeface bolded.
And:
But Jeff [Bezos] is not wired that way. There are very few people in technology and business who are what I’d call apex predators. Jeff is one of them, the most patient and intelligent one I’ve met in my life. An apex predator doesn’t wake up one day and decide it is done hunting. Right now I envision only one throttle to Jeff’s ambitions and it is human mortality, but I would not be surprised if one day he announced he’d started another side project with Peter Thiel to work on a method of achieving immortality.
As Eugene points out, the people who bitch and moan about the profitlessness of Amazon sound a lot like the people who bitch and moan about the slow, deliberate iterations Apple has with its products.