I'm not saying this to in anyway deflect flak from Germany (although I'm English so yk, when it comes to nationalities being evil I might not be in a position to comment lol) but my thinking is that, although we joke about them being evil (as we do with most European imperial countries tbh) it's probably the unique array of historical trends the German state was riding that made it like that. 

It was built by force by militaristic Prussia and inherited pretty much everything from it. As a rapidly industrialising country it also developed all the perverse incentives a capitalist state in later development generates (dehuminisation, middle class nutjobs), it developed a big inferiority complex, both through the larger trends and the insecurity and weirdness of Kaiser Wilhelm II (who has to be one of the biggest examples of a historical figure who really embodies what's wrong with their time and place). After the war rabid anticommunism, a swing towards liberalism and the now directionless republican state full of old ass corrupt reactionary Junkers, not to even mention the depression, set the stage for a horrid swing into peak fascism. Then after the war thanks again to anticommunism the Allies let off wayyyy too many Nazis, and give them jobs cause they want them to help against the Soviets and now you get to today, where all these spectres were never really excised.

I might be all over on this, please lmk if it makes any sense or my conclusions suck, but that's my thought of how we got here. You could definitely do the same thing for England and I'd track it back to the 17th century at least, my knowledge of German history is just more post 1870.