Fame
There have certainly been famous conductors throughout history and there are still some today.
The Leonard Bernsteins, the Toscaninis, the Dudamels—these folks are treated like royalty from the classical crowd.
However, their fame doesn't touch that of a teenage pop star who can sell out the Hollywood Bowl in seconds. It's a great gig if you love music—not so much if your goal is to play the halftime show at the Super Bowl.