Companies are not committed to employees. The easy example is that they have layoffs, even amazon and microsoft. a committed company would do what microsoft used to do, since they had basically endless openings, if your project was canceled you had 2 months to find another job. and you could always find another job.

The other reason to consider carefully before going there is they sometimes try to scare people by enforcing non-competes. So what are you going to do, deliver papers? Here's a recent article - https://www.geekwire.com/2017/business-personal-amazon-web-s...

edit - here's an example of layoffs in seattle https://www.seattletimes.com/business/amazon/amazon-laying-o...