I'll explain. There are 2 reasons why Prince wasn't famous:
1. He changed his name to that symbol during the 90s.
2. He didn't allow his music on YouTube. Many people use YouTube as a "try before you buy" for music. Before he died, his publisher would take down any video that had any Prince song in it, but now his music is all over YouTube so this generation gets a chance to listen to his awesome voice.