Gonna have to take issue with this. For the time, effort, and debt accrued, becoming a doctor is an awful financial investment, when you can go into business, law, investments, etc.
This may or may not be a controversial position on this forum, but I have a big issue with primary and secondary school teachers getting tenure. The whole point of tenure is that you prove your worth and then have the opportunity to innovate without fearing for your job. That's how you end up with the quirky-but-brilliant professor that each university seems to have at least one of. But at the lower levels of education, this seems to have reversed entirely, where tenure is a crutch (and, in some ways, a restriction). Once you get tenured, it's like a license to slack off, and the pressure to *get* tenured crushes the souls of fresh blood.
Obligatory disclaimer: Not all teachers are like this. In fact, I've had the terrific fortune of being surrounded by great minds both at the front of the class and in the seats alongside me.