Wikipedia has a good written summary of the con: https://en.wikipedia.org/wiki/Michael_Larson
The linked documentary is well worth watching, though.
The linked documentary is well worth watching, though.
As the documentary points out, they just didn't think that anyone would be able to "aim and hit" the square they wanted - but they were mistaken, and paid for that complacency. They did not make the mistake a second time.
Keep in mind that this happened in 1984. The board squares were physical panels, and the panel selection software was analog.
In gaming, a random outcome is one the player can't accurately predict or influence. The Press Your Luck board at the time fit that definition, but Larson proved that was not a safe assumption.