My farther has a degree in organization theory, and frequently encounters people who say they can predict the market, but often even fail to take into account their own interactions.

My father has a degree in Industrial Chemistry, my cousin has a degree in Visual Arts and those specific people that your father talks about are wrong. Most other people who claim to be able to predict the market also happen to be wrong---people are often silly and overconfident and markets are hard to predict even when only moderately efficient.

Nevertheless, the claim:

People who say "we can predict the market" are factually wrong, because the thing to do with a prediction is exploit it, and the moment you exploit it you invalidate your own prediction.

... is muddled thinking.