Yes, most bodybuilders are stupid when it comes to financial IQ. There are few "sports" that require such an investment of time and energy with very little payout. This is why most intelligent people do not pursue bodybuilding as a career choice.
Heres a newsflash for you...most (if not all) pro Bbers didn't begin BB as a "career choice". What happens 99.9% of the time is a guy starts lifting weight by whatever means they are introduced to it...finds himself making good gains, is introduced to competitive BB, finds himself competing...does well...gradually moves up the ladder winning local, regional, state, National titles....wins his pro card.
Opportunity then presents itself by way of sponsorsip by said company, and the BB finds himself in a position to make a good living from it.
ALL pro BBers share one inherent quality...NONE of us started BB for the money.