It's human nature tbh man. Our history has something to do with it as well, like descending from slaves, who descended from people from Africa that were sold.
Africans fought with each other, the English fought with each other, Italians fight with each other. It's human nature, and this idea of race has been so implanted in our heads that we can't see that. Of course you should be prideful of yourself and your race, but don't think it's nothing normal. It is.
Now the glorification and admiration of it isn't, and that's the problem.
Also systematic oppression as well, but overall people like fighting people.
Then they use a numerous amounts of reasons for why they don't like a person, whether it be their race or religion or height or smile.
And the mafia is glorified because it's a group of people who reflect the type of lifestyle that we admire. Gangster lifestyle.
It really depends on your angle, but the Italian mafia, especially the Sicilians may talk bad about black people, but go to Sicily and look at the people and the architecture and you'll see that it's just self hatred.