2) What we want changes over time: Human desires are not static. What you want today may be exactly what you don’t want next year. We’re not talking about moving the goalposts here; we’re talking about playing a new game. How many people go to college for four years to get a degree in a subject that they never spend a day working in for the rest of their lives? Plenty. It’s also very easy to start working your way up to the top of a profession and realize that you don’t like it very much. The same goes for getting the spouse you want and realizing two years in that he or she is really not whom you want to spend the rest of your life with. What good is superficially appearing to “have it all” if you don’t want what you have?
You can't always get what you want, but you get what you need.