Karl Haushofer learned the hard way how academic ideas can be used to twisted ends. His geopolitics was first studied by Hess who then passed it to Hitler who ‘pumped it dry’ (First we will conquer Germany and then the entire world.)
From Wikipedia: Lebensraum (“living space”) refers to conceptions and policies of a form of settler colonialism connected with agrarianism that existed in Germany from the 1890s to the 1940s. One variant of this policy was supported by the Nazi Party and Nazi Germany. Karl Haushofer provided the Nazis with the rationalisations (intellectual, academic, scientific) for Lebensraum, transmitted to Chancellor Adolf Hitler, by way of Rudolf Hess, who was Haushofer’s student.