Having hung around them before, I think it’s because what tyrants actually promise them is the right to be openly hateful without consequence. See, they believe drivel about how people different from them are the cause of their problems long before fascism shows up; they were always bigots and likely always will be. The fascists simply mirror their thoughts, speech and behaviors openly, making the followers feel safe to express shit they already believed.
It’s not the fascist leaders that are responsible, it’s the people for thinking the way that they do.