You really don't know that for several decades the Klan was celebrated by most Whites, North and South, as Christian activists who enforced strong morals and family values. Even people who found the killing of Blacks distasteful overlooked those killings because the Klan had occasionally protected a wife from her abusive, drunkard husband, or fed a neighbor bhen he was down on his luck. It wasn't until the 60s that any real pressure was put on the Klan, and then only because Blacks gained support from the "lefty" Democrats in Washington. Even then many local governments and churches sheltered them.
It's a lot easier to get down off of your high horse than it is to be thrown off.