A friend of the Corner writes:

I agree with you that he’s not doubling down — that usually happens in blackjack when the player sees good cards and a favorable matchup against the dealer. Doubling down is not what you do when you are losing badly, yet continue to play aggressively. There is a term for that in poker, however — it’s called being “on tilt.” Like a pinball machine, the lights are flashing, bells are ringing, and all the player is doing is betting and betting and betting. And losing.
The biggest problem a poker player can have is a simple confusion of the verbs “to think” and “to hope.” As in, I just revealed my pair of aces, and you say, “I thought you had kings.” I say, “No, you hoped I had kings. Big difference.” Of course, one could write a poker book about it, called “The Stupidity of Hope.”