There were psychological studies of Nazi war criminals using Rorschach tests and other instruments which don't have obvious face saving answers. The lower level were unimaginative people with a simple view of order and what was proper. Being drug addled would not have been part of that or their behavior. The higher level such as Goering were at least at one time drug addicts but not that simple minded. The fact that Eichmann put on the pose of a banal bureaucrat,
Adolf Eichmann was, of course, in no way a banal bureaucrat: He just portrayed himself as one while on trial for his life. Eichmann was a vicious and loathsome Jew-hater and -hunter who, among other things, personally intervened after the war was effectively lost, to insist on and ensure the mass murder of the last intact Jewish group in Europe, those of Hungary,*
suggests a readily available pose or personality. Perhaps the rebellion inside that personality struggling to get out would find some identification with the Hebrew meaning of Isra el, he fought with God, but not having in some sense survived the fight with the internal imago of their parents, hate Israel and Jews for having done so. I am not familiar with Galbraith's report though.
* Ron Rosenbaum's article in Slate with better picture of Hannah Arendt.