Top managers wages are completely fictitious. Investors generally don't care though, since it is basically nothing compared to turnover as a whole.
I believe as an American I’m missing some important context to understand this comment.
The purchasers (taxpayers) are not willing to pay sufficient wages in order to incentivize [the right] people to pursue it as a career.
For those remaining 25 years, they will tend to prioritize money in their pockets over a teacher's salary; a situation that does not align with the betterment of our society at large.
The million dollar teachers will do things like actively manage the student's home life or business trajectory, give them personalized curricula, connect them with opportunities to gain hands-on experience, etc.
Not saying you're wrong re: the incentives or anything, but a lot of people don't even know this segment of the market exists.
You have named the very reason the teachers are angrily protesting any and all attempts at evaluation of teachers' productivity. Or introduction of private (i.e., market-based) schools competing with the state run ones.