At what point does defending one's ideals turn to indefensible hysteria?

Defending one's ideals turns to indefensible hysteria when one has power. Adolf Hitler, gaining power, tried to exterminate the Jews. Accusing others of witchcraft during the Salem Witch Trials, the people of Salem gained power. A person could accuse another person, without evidence, of witchcraft. And the accused person would be hanged or thrown in prison, just because they were accused. The townspeople turned into monsters, hanging nineteen people without reason.