The batman effect
Photo by Action Vance
It's been demonstrated that thinking of oneself as an alter ego helps with resolve and perseverance when performing a difficult task and well-known artists like Beyoncé and Adele have used it to overcome stage fright for years.
That explains David Bowie, Madonna and Prince who each have been re-inventing themselves throughout the decades, over and over. While I don't know if they were consciously employing this trick to boost their confidence on stage, it's hard to imagine that Ziggy Stardust didn't have a similar effect on the quiet Bowie.
If you try it on, just don't pick a politician.