You should read that as a self-preservation technique. The eager use of a strawman tells us PG heard AOC's words as an attack against him personally, his business, and his friends.
So the essay is not a reasoned retort but more an emotional self-defense to soothe a bruised ego. It's to assure himself that no -- in fact he did earn his wealth fair and square, and to imply otherwise shows a lack of understanding of how this all works. But I do love this essay because it does show just how emotional and irrational billionaires can be when their wealth and egos are threatened.