For white Southerners I boil it down to not wanting to admit the old romantic stories about the war and the bravery were for a shitty cause. In the Civil War years, no problem admitting that you’re fighting to protect slavery staying legal but even by the 1880’s when Jubal Early started the Lost Cause and certainly by the 1930’s when Douglas Freeman wrote his Lee biography, slavery was seen as ugly by the public as a whole. I think it’s similar to how people like D’Souza attempt to make evil groups like the Nazis, Klan, Jihadists, etc comparable with modern liberals because they can’t sdmit their ideology has more in common with the broader points of those three and to admit that would be to acknowledge the flaws of their ideology and they’re not willing to do that.