MAGA is popular for the same reason other nationalist, fascist movements have risen over the course of modern history: as a response to Capitalist decay. MAGA isn't popular for genetic reasons, intellectual inferiority, or other reasons like that, but as a common class interest.
Fascism is most often represented as an alliance between the Petite Bourgeoisie and Bourgeoisie proper, driven by the Petite Bourgeoisie, as monopolization of Capital results in competition becoming more and more difficult, and the Petite Bourgeoisie faces Proletarianization. To prevent the Petite Bourgeoisie from joining the Proletariat in solidarity, the Bourgeoisie proper turns their hatred against the Proletariat and Lumpenproletariat.
What does this all mean, in practical, American terms? Small business owners, landlords, ie the "middle class," is shrinking in power, so the Small Business Owners are aligning with billionaires like Musk and Bezos against immigrants, workers, unhoused peopled, gender/sexual minorities, women, ethnic minorities, and more.
How do we fix this? Grow the Petite Bourgeoisie and restore their position? Absolutely not! That's when fascism is established. Trying to "turn the clock back to the good old days" results in dramatic reductions in worker rights and a solidification of power.
What we need to do is establish Socialism. A victory of the Proletariat, a folding of the large monopolist syndicates into the public sector so they can be centrally planned for the public good, rather than privately planned for profit, is the way forward. This is the way to escape fascism's rise. This is the way to defeat MAGA. I recommend reading the book Blackshirts and Reds.