Although told at the beginning of the story that he has unlimited credit, Franklin is chided for writing multiple checks for gambling money, incurring a large debt. Why would he need to write checks if he had unlimited credit? See more
Mr. Franklin Gibbs, visitor to Las Vegas, who lost his money, his reason, and finally his life to an inanimate metal machine variously described as a one-armed bandit, a slot machine, or, in Mr. Franklin Gibbs' words, a monster with a will all its own. For our purposes, we'll stick with the latter definition - because we're in the Twilight Zone.