There's plenty reasons other than work that you might resign a perfect job for. For some people, hobbies are more important than jobs, and those hobbies might include traveling around the world, living in a different country, etc. Similarly, some people value family over work, so if their family relocates they would go along as well, giving up their job.

But even in just the realm of money and career, there are companies that offer benefits beyond money - like a certain freedom and culture - so you might feel "properly compensated" there. A monetary crisis(children, health issues, accidents..) could easily force you to take a higher paying job and leave your dream workplace, though.