The entire story, not just the ending, is all in Radin's head
- He was hallucinating his entire encounter and staged scenario, when in truth he was never a millionaire or even a mildly successful man at all, but a pathetic, mentally ill man who is wrecked by his past and his own personality flaws.
The three authority figures had a My God, What Have I Done? moment when they found out what happened to Radin
After being relieved they didn't die in a nuclear explosion, of course.