What you're failing to understand is mathematical logic.
We're assuming the guesser only gets one guess. I agree that the guesser has a 100% chance to get the dollar 25% of the time, as weird as your wording on that is.
You could paraphrase that to make more sense: The guesser definitely has a 25% chance to get the dollar that is 100% in one of the 4 pockets.
In order to have a 100% chance to get the dollar, the guesser would have to have 4 guesses with a 25% chance per guess, assuming the guesser never guesses the same pocket twice.
Since the dollar is present at all times, there is a 100% chance for the guesser to get the dollar no matter what pocket they guess.
If the dollar is in your front right pocket, and guesser guesses that the dollar is in your front left pocket, the guesser will never get the dollar. That is why your logic is wrong.
