James Stewart had a good movie "The Jackpot." Not sure if it was based on any particular radio show.
For the sake of the three of us who care about this and want to Horanically show off what we know:
I'm pretty sure they fictionalized
The Jackpot, but it was based on a true story that appeared in
The New Yorker about a guy who won an absurd amount of merchandise on
Sing It Again and struggled with paying taxes on his winnings.
There was also a movie version of the radio game show
Take It Or Leave It.
The best of the lot, by far, is
Champagne for Caesar, a comedy about a genius (Ronald Coleman) who is wronged by a soap company president (Vincent Price) and decides to take revenge by appearing on a double-or-nothing quiz show they sponsor. For the sake of the plot, the fictional game show put no limits on how often you can "double", and he threatens to bankrupt the company.