Why didn't Stempel just take the money and run?
If Herb Stempel knew that they would make him take a dive, why didn't he just retire from the show instead the next episode?
This way, he would have kept his winnings, and wouldn't have to humiliate himself. The money he made was a lot more than he had seen, and he would have still had his pride and integrity.
Also, the producers win, because they would have got Stempel off the show anyway, and then could work to have Van Doren on, without having to worry about Stempel.