revenue is not profit and has nothing to do with it.
amazon does NOT, I repeat, NOT make a reasonable profit, compared to their revenue.
they do (and have to) invest most of their earnings into staying ahead.
it does have, however, billions from investors. as long as these investors are happy with the shareprice, amazon will survive.
10 yrs ago they started at 34 USD, today they are at almost 700 USD (source: yahoo)
that share price is based on turnover (revenue) and gutfeeling.
what the balance is between the two, is anyone's guess...