The prize was paid out at $50k/year for 20 years. After taxes, that could cover a modest living in many parts of the country, but I'd agree that is not "quit your job/retire" money, even in the 90's.
The story calls him a "A $5-an-hour office supply store salesman", so at 2,000 hours a year it's $10,000. That makes the gross prize money five times his salary.
He could easily have paid for someone to attend Harvard on the prize money (https://www.thecrimson.com/article/1990/3/20/ivy-tuition-rat...).