Money is just a way to keep score. The best people in any field are motivated by passion. That becomes more true the higher the skill level gets.

People are happiest when they're the most productive. People enjoy tasks, especially creative tasks, when the tasks are in the optimal-challenge zone: not too hard and not too easy. To some extent, that has always been true. But it becomes even more true as work becomes more about brains and creativity.

When are programmers happy? They're happy when they're not underutilized - when they're not bored - and also when they're not overburdened with inappropriate specifications or meaningless bureaucracies. In other words, programmers are happiest when they're working efficiently. This is a general preference in creative work.

Eric S. Raymond Quotes