I don’t think capitalism is necessarily at fault, nor must the working/middle classes be struggling for fascism to emerge. If anything, quite the opposite. It is the better off countries that end up turning fascist. All fascist countries are/were first world countries, in various states of advanced development.
That’s not right, at least not for the fascist regimes in Europe that emerged prior to WW2. The countries where it happened (specifically Germany/Italy/Spain) had all seen civil unrest or even civil war in the recent past, they were hit hard by the global financial crisis in the twenties and had high unemployment and widespread poverty. This was the very thing the fascists used to ingratiate themselves to the public at large, by creating jobs through massive public building and rearmament projects.
By the way “first world countries” is post-WW2 terminology and didn’t originally have a connotation of superior economic status, but was referring strictly to ideological alignment. Whether a country belonged to the capitalist/communist/unaligned block in international politics during the cold war.