Psychiatrists insist that only individuals can become psychotic and that when an entire society does bizarre, destructive things--you can't call this psychosis as long as it "fits in" with the cultural norm.

However, if you read the transcript of one of Goebbel's typical pronouncements (see his speech below), I think you'll agree  that the phrase "psychotic delusion" is not inappropriate.

Richard Koenigsberg

Joseph Goebbels, essay of November 16, 1941.
“The Jews are Guilty”
“Every Jew is our enemy in this historic struggle, whether he vegetates in a Polish ghetto or carries on his parasitic existence in Berlin or Hamburg or blows the trumpets of war in New York or Washington. All Jews by virtue of their birth and their race are part of an international conspiracy against National Socialist Germany. They want its defeat and annihilation, and do all in their power to bring it about.”
The Holocaust took the lives of
approximately 5,962,129 Jews.