When we were hunters and gatherers and Nomads, it made sense to be afraid new groups of people. Back then, we didn't have access to information about other cultures. They could be cannibals or Raiders or anything.

But while times have changed, some people haven't. They brought the fear of tribalism into the present day and react with that same wearing this to anyone who doesn't look, worship, or love in the same way they do. Rather than go outside their comfort zone and learn about people who are different, they take the Cowardly way out and Surround themselves with a bubble of racism, homophobia, and xenophobia.

To further ensure that they never have to deal with anyone different, they want to make the place they live as inhospitable to those who are different as they can. When their leaders turn out to be Mass murderers, they fear the consequences of having to admit that they were wrong, so they never will. When they realize they're racist, homophobic, and xenophobic worldview is wrong, they will never change because then they would have to admit that all the people they hurt in service of those beliefs did not deserve the way they were treated.

Just as their leader would never, ever admit to having made a mistake, neither will they.

That's just how cowards are.