I feel like the saying "nothing to fear but fear itself" is appropriate here. In part because fascism is a mental illness triggered by an overabundance of fear, but also due to the fact that fascism if contained is self-defeating.

A fundamental feature of fascism is the continuous shifting of rhetorical focus, their enemies are simultaneously a powerful cabal that runs the world and genetically inferior untermensch. It's impossible to for the fascist to adequately assess the ability of their enemies; their propaganda demands an unreasonable uncertainty. The core of fascism is a profound lack of understanding, both of the world at large, and of accurate self-knowledge. It is not coincidence they are lead by narcissists and driven by an obsession with impossible conspiracies.

They have no solutions to the causes of the problems affecting the people, and rely on scapegoating to draw attention away from this. And as they begin to run out of scapegoats, they must create new ones from within their own body. A fascist regime can never ultimately win, it will always discover new enemies to further cannibalize itself. It is the ideology of self-destruction.

Success in fascism comes from the eager collaboration from liberals. Germany before Hitler had immense labor power and military expertise. As the war drew on, Hitler trusted his generals less and less, and took more and more control of the details of governing of the country. He made so many unforced errors that it was determined by the allies that further assassination attempts on him would be counter-productive to a swift end to the war.

Fascists can win just as much as cancer can win. If it reaches its natural conclusion, it dies with its host. We have much more experience dealing with fascism; we know how to defeat it. Tyranny doesn't succeed on the virtues of the totalitarians, but the failures of the liberals. Narcissistic leaders like Donald Trump will continue to waste their resources and undermine their movement. No matter how much they appear to succeed, they are bound to lose; but the damage they do with each success means we need to fight regardless.