One of my favorite quotes of all time came from a psychiatrist, speaking on Mel Gibson's famous drunk driving tirade:
"You can't pour vodka on a turnip and have it say anti-semitic remarks."
However, Bowie claims it was a stage persona. Why he decided on a fascist for the persona is a decent question on its own, but I don't think "because cocaine" is a good explanation by itself.
The Thin White Duke was the persona and character adopted by the English musician David Bowie for public appearances in the mid-1970s.
[…]
The Thin White Duke became a controversial figure due to ostensibly pro-fascist statements made by Bowie in press interviews during this period. Soon after making the comments, Bowie claimed that they were "theatrical" remarks made in character and did not reflect his actual views.