Your analysis is rigged just as much. It was not a rigged study, it was asking a specific question, because that’s how research work.
Would you prefer it if they specifically selected drug addict and long term unemployed people? But what would that experiment show? Absolutely nothing, unless you happen to not know yet what drugg addiction or depression do to people.
When you say it was rigged, you demonstrate that you don’t understand the question that was tested in the experiment.