Having a high IQ doesn't automatically translate to being a genius. It just means you're capable of it if you put it to use.

FWIW though, Dolph Lundgren does hold a master's degree in chemical engineering, which he got from the University of Sydney. He had also received an MIT scholarship shortly after, and then left it all behind to pursue (at the suggestion of his then girlfriend Grace Jones) an acting career. He's definitely not as much of a meathead as his appearance would lead one to believe.