The essay starts out with a good premise, but in the end, he seems to have conclude that "fair market price" is equivalent to the added value to the society of the job. That seems quite a bit off of a conclusion to me.
Not exactly. I read "I know this because of all the money they give me" as somewhat tongue-in-cheek, like he's saying something he wants to believe, that the world tells him to believe, but cannot help questioning the truth of.