Basically, Amazon forgoes profit to get market share, will push out all competitors, build a huge barrier to entry with excellent execution and logistics, and then raise prices to increase profit. Traders are buying now and holding until that happens.
I'm not exactly sure what the deal is with Amazon, but their p/e was much more realistic in the not-so-distant past:
Ratios have to be considered in context of expected future growth and expected future profit margin (revenue grows a little but profit grows a lot). Even considering that, some ratios seem extreme.
FB Forward P/E: 44.85
FB PEG Ratio: 1.67
AMZN Forward P/E: 85.52
AMZN PEG Ratio: 5.92
CRM Forward P/E: 69.06
CRM PEG Ratio: 3.29