Remember that racial segregation in the US wasn’t that long ago, historically speaking.
Some of children who lived through that era were raised with racism and these values were passed to their children who became Gen X and Y.
Religion also had a bigger influence in the previous generations. Homophobia and transphobia was normalized and you could even be arrested for being any of LGBTQ up until very recently and it’s still the case in some regions.
Nazi ideology never really left either. And the way this ideology came to be was through disenfranchised people who were angry and needed someone to be angry against. Someone came at the right place at the right time and gave these people a scapegoat.
Fascism is kind of the same but with a cult of personality.