It's not obvious that land was valuable enough to fight a genocidal war over. I mean Germany has a bigger population today than it did then.
But Hitler wanted a genocidal war, so he had to come up with some reasons to bolster the case.
But Hitler wanted a genocidal war, so he had to come up with some reasons to bolster the case.
That is the easy answer. The west, due to cold war realities, has placed far too much on hitler's shoulders. He was evil but no comicbook supervillain. By blaming everything on the core nazis, most all conveniently dead, we can more quickly forgive everyone else. The reality was that they each stood atop a large social structure. They were products of history, not super-evil monsters dropped into the scene deus ex machina. It is too far to say that "Germany" wanted genocide, but the answer has to be somewhere between the bookends of "Hitler wanted X" and "Germany wanted X".
Well thats the point. Because even if todays borders are considered "untouchable" through international law, that was not so much the case in the beginning of the 20th century.
In fact re-drawing borders was exactly what seemed a completely legitimate way to "penalize" Germany/Austria for the Great War. So it is no wonder that Germans had no hesitations about the "land-grabbing" part of Hitler's policy - land grabbing was totally legit, ey?
Of course, putting those guys in charge of operation land-grab which had the most vile hatred of them all was on part of the German populace naive at best and complicit at worst. But then, what opposition to expect, if the Nazi-genocide's first victims were Germans, basically muting almost all opposition by emmigration or death.
Also, about the in retrospect outlandishness of the Germans for wanting to grab land from its neighbors - what did Germany's contemporaries do right after WW2? Demanding to shift some borders: The USSR+UK at the expense of Germany and Poland with Germany loosing 30% of its territory. France incorporated itself the Saarland. The Netherlands wanted to increase itself by ~30% at the expense of Germany. Belgium had plans for annexation and even tiny Luxembourg saw fit some expansion.
Secondly, what of his twisted advisors? I think it would be fascinating to read tertiary literature of sentiment in that era and how people with those sentiments gained influence.
Secondly, the 'twisted advisors' shouldn't be seen as a few extremists, but rather the then-current alumni of a school-of-thought that was in the making for at least hundred years before WW2: Reactionary nationalism driven anti-semitism (as opposed to the anti-semitism that roamed europe before the 18th century).
Within these 100 years multiple people discussed 'solutions' and often the legitimate ultima-ratio seemed to be capital punishment, if the Jews weren't leaving by other means (As today some politicians would legitimize shooting illegal aliens at border-crossings).
All the anti-semites need to do to gain influence was to add fuel to the flames of the 'treason'-narrative.