They really want to turn into a logistics company.

Amazon packs, warehouses, and delivers your package acting as payment manager, and customer service while hosting your IT infrastructure.

They want to sell pickaxes and do laundry for gold miners.

The part where Amazon isn't packing and shipping your product is a weak link – killing fake reviews helps this though.

For what it's worth eBay does turn a profit most years: http://www.marketwatch.com/investing/stock/ebay/financials

There's a lot more profit in being a platform than a retailer. Amazon is letting other parties use their platform to do the high-capital, low-margin, race-to-the-bottom retail side and taking a massive chunk out of each sale. This is much more lucrative than sourcing, building, buying, and storing items directly.