The very counterintuitive conclusion from Deeyah Kahn's films that broke my brain is that denouncing them often contributes to their radicalization and anger.
The thing is they are people who have not gotten validation from their lives — respect, friendship, a sense of purpose, of belonging, importance, appreciation. The alt-right recruits people from hard circumstances like broken homes, areas of urban decay, a struggle with life.
When they are recruited, they are told Jews, Muslims and immigrants did this to them and seek the extermination of the white race. The best recruits have never met Jews, Muslims or immigrants. The recruiters give them a sense of belonging and purpose. These guys have felt unaccepted all their lives and now they feel the liberals disrespect them.
You could see in the film how meeting Deeyah, a Muslim woman who listened with respect and was nice, broke their brains. A few of them left the movement, saying they had never met a Muslim and didn't realize they could be friends. Those who left said the best thing that ever happened to them was meeting the people they thought they should hate and make friends with them.