Don't forget, the fascist rallies also had one incredibly important thing that drew in more people than the free food and free beer - a simple, targeted reason WHY they're in the shitty situation.
You can throw as many economists and scientists and such at the problem and they'll (properly) show the reasons, but there won't be a simple solution. There won't be a singular "here do this and it will magically fix all your issues" point. Even the simplest fixes to the situation will be overwhelming for most people.
And most people just want that: a leader who promises to solve the crappy situation, without making them feel stupid, without convoluted long drawn out plans. A simple solution, a simple fix.
For Hitler that was "get rid of the Jews". For mango mussolini that's "get rid of the illegals".
And people liked the simple solutions so they signed up for the ideology.