Update : To people who ask why would someone need another job?
There are multitude of reasons, a well funded startup which could pay several times the industry standard - when fails; puts excessively paid employees to compete in the same standarised job market. If you live in the part of the world where the HR asks about your previous pay to assess your eligibility for current job, you will soon end up settling for a sub-par(quality) job with standard pay i.e after giving up the ego. Also if the high paying job didn't provide you with necessary foundation to consistently improve your skill set, the moment you are out to compete in open job market; you'll be facing tough competition from better skilled people with standard pay whom the companies would likely prefer. Again, my arguments are based on the fact that you live in part of the world where your previous pay matters for current job interview.