[mfrommil]

They can get it right (figure out how to increase order sizes, order frequency, margins, etc.) and then expand; or they can expand and try to figure all of those things out.

With their main business they chose to grow as fast as possible and are still figuring out profitability. When you're selling electronics with 50% markup that works. Groceries, which have <5% margins, not so much.

[kinofcain]

Sort of. Amazon started out with just books, they got that working and then started selling everything else. But for a long time it was just books.