Roots of national-sociopathy are, obviously, in German nationalism preached by – among others – Georg Ritter von Schönerer and Dr. Karl Lueger – political heroes of Adolf Hitler.
However, it was markedly reinforced and dramatically radicalized by armed robbery at Versailles (where Germany was forced at gunpoint to cede large territories to France, Poland and other nations) and by the existential Bolshevist threat.
The key deficiency of national-sociopathy that ultimately led to Nazi defeat in World War II, demise of the Third Reich, suicides of its Führer (and other prominent Nazis) and the (in)famous Nuremberg trials was its deep (and totally erroneous) belief that politics was a zero-sum game.
It isn’t. Actually, the three keys to success in politics are to (1) make as many friends and partners as possible; (2) pursue win-win situations wherever possible – in most cases it is; and (3) do not make new enemies unless absolutely necessary.
Nazis were totally capable of keeping the USA out of World War II (by skillful diplomacy) and of establishing win-win partnerships with the general population of Russia, Ukraine and Belarus (by becoming their genuine liberators from brutal Bolshevist dictatorship).
Unfortunately for the Nazis, both were totally incompatible with their national-sociopathy (i.e., national-socialism). So instead of making new friends (or at least guaranteeing the neutrality of “all of the above”) they created very powerful enemies. Which ultimately cost them their war, their civilization and for many – their lives.