Again, it’s a spectrum

A spectrum from evil to stupid? Nah. There can be two spectrums at play, one of evil and one of stupidity, but not a single one. These categories are not mutually exclusive in any way, and usually Nazis show high scores on both spectrums. I have yet to see one Nazi who's not stupid, and that includes both Trump and Elon Musk.

I would argue that a Nazi is inevitably evil, and being stupid is a prerequisite of being a Nazi, because ultimately it's a self-defeating ideology that requires stupidity to believe in.

they understand that they're shooting themselves in the foot, they decide it's worth it because they're okay with their suffering if it means certain other people are dragged into suffering with them.

The old zero-sum mentality. If others' happiness decrease, theirs goes up in comparison, because obviously there's a rigid societal hierarchy and they must force others down to stay higher up.

I remember hearing about a study years ago where people were basically asked (IIRC) would they rather earn $80k a year while all their F+F earned $70k, or $90k with their F+F earning $100k? A significant minority chose the former, which just fucking sums up the desire to be perceived as 'better' trumps actual tangible benefits.