Definitely not rare, more like malignant, aggressive, terminal..
But the cancer analogy does work, because you can't cure it with band aids (like elections), you have to cut the fucker out at its core, radiate the remaining tissue to make sure none is left behind (via education and a complete overhaul of how society functions, with zero tolerance for bigotry), and continue to get regular check ups to make sure it hasn't returned, and if it does, radiate the fucker again before it metastasises.
The truth is WWII wasn't fought over bigotry and hate and the fact that people were being exterminated on an industrial scale, it was fought so those in power could stay in power and maintain the status quo, and also make a handsome profit. War always is.