Well, my belief is that it was never defeated and has become the dominant form of governance around the world.
Long before fascism existed, during the American Revolution we see how the wealthy oligarchy manipulated peaceful colonist into a violent revolution. Shortly after this the first President was sworn in who was a military commander and also one of the more corrupt people in US history.
We see the intersection of a controlled economy run by the wealthy for the wealthy combining with the military to create the first truly fascist nation. A nation that later went on to perpetrate a genocide.
You have to be able to separate propaganda from reality and it is not easy especially for me as I was indoctrinated into the cult of the US.
When you start seeing the government as an illusion to maintain control you begin to make sense of things like the US overthrowing countless democratic governments to install fascist leaders during the Cold war.