Some of the best programmers I have met left higher paying jobs to do something that at least somewhat changes the world for better or helps people.

This is about the vertical within our horizontal discipline. Working at a marketing company will be very different than defense. Some people want to work with visually appealing things, some people will only be happy if their software helps people. Don't blame the CRUD (cleaver play on words though). If you are truly a developer and find the horizontal you love you will be glad to work on it's CRUD.