The following is from the book "Evil in Modern Thought" by Susan Neiman. (page228)

"For nothing works so well in getting someone to give up a position as making him feel ashamed of it."

Once one becomes emotionally invested or ideological in certain views, suasion has little effect.
It took the calamity of total collapse to break the fever of the Riech's Nazis.
And even then, many went to their graves as true believers. Publicly calling 'their' monstrous crimes contrived falsehoods/propaganda, while privately fiercely proud of what 'they' did.