Jeff's strategy is to get the better people, give them a high wage (usually about top 20% of the bracket), and then work them with intense stress, and fire the bottom 5% every year.
I was there, and to be honest the pay is not good enough to stay. If you want to work harder for the same condition there're better pay jobs for the same stress level (i.e. Facebook, Netflix), or same pay for less stress (Google). It is a good experience to have if you just graduated, you'll learn a lot in the fire than in a cushy job.
Buying Amazon stock while Jeff is still in charge is a good bet though, their internal projection is it should go up 15% a year. They spend every profit earn to build the company bigger, instead of dividend.