No matter how preposterous, these rumors persist. We want to believe them. Like all myths, these represent elements in human psychology that we don't completely understand.
The Devil's Counterpoint
First, great talent clearly bothers us. The appearance of genius is disturbing on some level and we have to account for it. Musical gifts like Paganini's or Johnson's is like a lightning strike -- powerful, wonderful and terrifying. They highlight our own weaknesses, our inadequacies, our mortality. Calling it evil and unnatural makes it a lot easier to swallow, especially if we loop in eternal damnation for the Uber-Freak. Second, the Devil story isn't told about every talented or famous musician. John Lennon, but not Paul McCartney. George Gershwin perhaps, but not George M. Cohan. Only the hip few are chosen. Squares need not apply. There is something subversive about each of these artists, an air of danger. The playing style is daring and supremely confident, the lifestyle often reckless. Where the rumor is strongest, the music is also invasive, punching through the comfortable envelope of polite, established style to touch us in a very personal way. It's sexy dark, like a vampire coming right for us, homing in on a vein. Third, the Devil apparently doesn't give every soul the same terms. Paganini lived into his 50s -- a good, long life in those days. He was one of the most famous and wealthiest musicians in the world at the time of his death. Hendrix was equally famous in his time, if not so wealthy, but died at only 27. Also 27 when died, Johnson was relatively unknown, a wandering performer living hand to mouth, who almost accidentally left a body of recorded songs.