The reason neofascism won was obvious. I would argue that it was the inevitable result of the Red Scare, the implementation of neoliberal economic policy after the collapse of the USSR, and the tendency of capitalism towards crisis. Let me explain here:
The Red Scare served to embolden capitalist hegemony in the system, and discourage even the most banal social democratic policies from being implemented. Without the destruction of working class politics, the neoliberal consensus and the pervasive hegemonic concept of "capitalist realism" would never have taken shape. This had a global effect, rather than a merely localized effect, due to US imperialism
After the failure of the USSR and the lethal "success" of the shock doctrine in the former Eastern bloc, the entire Western world jumped at the opportunity to double down those concepts as well, accelerating a tendency towards austerity and deregulation that started in the 70s. Those policies caused a horrific decline in living standards and health services, while causing a dramatic spike in inequality. This set the stage for both Putinism and Trumpism
And, last but not least, capitalism itself is an unstable system, and it is essentially impossible to stop it from crashing, taking all of us with it.