Prince wanted people to call him Prince. He changed his name to that symbol to get out of a shitty contract with Warner Bros.

“Warner Bros took the name, trademarked it, and used it as the main marketing took to promote all of the music I wrote,” Prince once said in a press release. “The company owns the name Prince and all related music marketed under Prince. I became merely a pawn used to produce more money for Warner Bros.”

https://www.bbc.com/news/magazine-36107590

Elon changed Twitter to X because he’s a babyman who never got over the fact that PayPal didn’t like the name.