I'm not saying money isn't important, but for people that that grow up as very successful students, the feeling that others don't see the university-level schooling required for their career path as difficult or prestigious tends to be a really major bummer. To me, that feeling was much more powerful than considerations of salary. I don't regret going to school to become a teacher, as that was what I wanted to be, but I can't say that I don't sometimes wish I could see how I handled the crucible of, say, medical school. (Note: I know that simply being a successful student doesn't make you a great teacher, but Finland does seem to require it as one element of the selection process.)