Why is it a common trope that college professors and teachers are "poor"?

The available data shows the wealthiest group of people in human history are actually highschool teachers and have the highest rates of making it to 7 figure net worth. They also have some of the lowest working hours and most paid time off.

College professors too have upper tier incomes in large numbers and many own side businesses/consulting. When compared to the actual median person they're light years ahead in earnings, wealth and the working conditions.

The actual normal working age adult isn't even likely to hold a full time job in 2022.

Is it a failure to do the math correctly? Inflated/self reported numbers from loud mouths who claim they make 250k a year house flipping at bars or the 1% of the 1% of ceos pulling 7 figures for a few years in their prime in the headlines...?

I have also personally met several professors who're clearing 7 figures annually, and at least one who has a good chance of being a billionaire in a few years.

pic related, was at some point a highschool math teacher.