I imagine that people in management positions have reason to take the package even if their skill set is perfectly aligned to the new job. If you're on a career path where one of the major measures of your success is how many people are under you, then you better be pretty committed to the Zappos vision if you're staying on. A long stint of not having anyone reporting through you might be a bit of a black spot on your resume if you ever end up for a position elsewhere.