They construct an ideology where everything was great way back when foreign powers were jealous of our national heritage and destroyed everything. It's a very easy to grasp and convenient myth, since your nation becomes the main character of history.

Nationalism/patriotism is very succeptible to falling for fascist ideology. Therefore, everyone waving their national flag with pride is sus to me.

Same thing any "in group" feeds on: self esteem. If you feel powerless, or worthless, or rudderless, any group that makes you feel powerful, valuable, and effective is going to be very appealing. Conservatives (read: fascists) prey on this. They make it seem like joining them is brave, and important. And since their followers lack identity and purpose, their self worth becomes entangled with [in group], be it closeted fascism such as the American GOP, or flaming such as Q/proud boys/whatever. And since their identity and value depends on the perpetuation and proliferation of their in group, they willingly accept lies and falsehood. Pretty easy to gaslight someone who's encouraging it.

Then when they wear their symbols of hate, or make shocking claims, or in anyway troll and grief society, up to and including dismantling democracy, they get a reaction. They've exerted their will on the world around them, and as such they feel powerful. The insidious bit is, even if the good guys win, with all their high falutin factual arguments and social programs, it just makes these sad people angier and feel worthless again. So they go right back to their pimps for some more sweet lies and marching orders.

Fascism preys on the ideas of regime change and stagnation. Physically, a government wishing to gather power through voters will promise new public works, a focus on workers, and the general embetterment of society. Ideologically, fascism promises a purging of those in power, those that lead the stagnation and bad working conditions that started the movement. They conveniently pin in on a group of people or a few undesirable groups to appeal to a large number of the population and then make a grab for power. Bad times and stagnation create fascism.

They are looking for a community that accepts them. That's why they are usually from broken poor white people with drug problems. Their parents are absent in many ways and are looking for somewhere to belong.

It provides easy answers.

You're a good strong person. They're bad people. All your problems are their fault

Most people love feeling like they're part of a group.

People want quick solutions to complicated problems. What quicker solution is there to all of your problems than blaming it on a disadvantaged group of people and persecuting them for it?

They never realize it's not an effective solution until they're way too established in the "kill the X" mode.

Why are you assuming most people care or are capable of reasoning about some vague "future"? Right now they feel disenfranchised because right now some is getting uppity.