'But when your profession
Is humiliation'
Could be interpreted two ways - either it is humiliating for the teacher, or their profession involves humiliating others (ie pupils).
The chorus is a big one, it could either be a statement or a threat.
There is definitely some sympathy there, but one interpretation of the lyrics as a whole is that he is simply explaining the origin of the behaviour from teachers he has criticised in the past. That is, he is saying teachers act hatefully simply because they are scared. It is probably M's history of anti-teacher statements and songs that make me read into it in that way, but I can't help but hear the chorus and wonder whether M is quoting or saying.