Literally, fascism isn't really a fully-fleshed out ideology and it doesn't happen on its own. Without wealthy/powerful backers, a bunch of parking lot racists are precisely that - violent losers are dangerous to your person, but not to a whole society. Fascism is a tool, used to maintain power for a ruling class that can no longer do so with the traditional levers of a "liberal democracy." So what changed? Simple, most of us know the planet is boiling because capitalism and we're all wormfood.