The way Germans followed Hitler and the Nazis and tried to occupy Europe and exterminate Jews seems really weird in a way. Even just looking at Hitler's speeches he seems obviously messed up, and it is weird that people found that charismatic and followed him.
The only explanation I can think of is that there was a lot of anger in German society at the time, and that Hitler and the Nazis were a good fit for that anger. People were holding lots of anger inside, and the Nazis gave them a way to express it into action.
I cannot imagine why people would have followed Hitler, started that kind of war, or fought it the way they did without anger motivating it. Even ignoring the moral and ethical considerations, the war seems to have been fought in an impulsive and not very intelligent way.
The short answer is that most people are happy to go along with things.
WW2 was not popular in Nazi Germany. When WW1 broke out people in the street celebrated about the impending glory. When WW2 broke out in Germany it was quite a contrast in that people were somewhat stunned and disheartened. Morale improved after a string of crushing victories against the Allies, but to think that the Germans greeted the war itself with great enthusiasm isn't really accurate.
As for anger in society, you have to expand your understanding of the excesses of WW2 and the Holocaust. You cannot simply localize it to Germany, as people from all over Europe collaborated with the Nazis to an extreme degree. It could not simply be an expression of German anger for people in France, Poland, Netherlands, Scandinavia, the Balkans, Russia, the Baltic states etc to actively participate in a genocidal war.
If you think these things are "messed up" (and they are), then you have to widen your understanding of warcrimes. Though the Axis killed more people than their enemies, millions of civilians and prisoners were murdered by the Allies, who didn't need to follow Hitler to bring themselves to commit atrocities such as:
- Firebombing and burning alive women and children and entire cities from the sky
- Massacring prisoners of war for "revenge", expediency, or simple amusement.
- Mass instances of gang-rapes, torture, and murder of German (and Allied!) civilians in Eastern Europe.
- Ethnic cleansing of Germans, and other ethnic groups of suspect loyalties at the end of the war
- The mass shooting and coverup of the murder of 20,000+ Polish prisoners at Kaytn
-Torture, abuse, and sometimes murder of (suspected) collaborators and their children in the aftermath of liberation
Note that I am not condoning any of the Nazis behavior, but just realize it was an absolutely nasty war and was fought with brutal means from both sides who were more than willing to kill unarmed prisoners and civilians in staggering numbers. If it was 'anger', then it was in all of humanity all along.
The truth is that most people were NOT very enthusiastic about personally slaughtering people, but that they did it anyway. Sometimes it was on a whim. Sometimes it was following orders. In all cases it was committing murder with the expectation that it was necessary, or profitable, or vindicating, or amusing, but that they were doing it 'for the state' and that the state wouldn't punish them for it.
It is little known that the gas chambers were in some way designed to help the Nazis kill mass numbers of Jews in a way that allowed the men to keep their conscience. Earlier in the war the preferred method of murdering 'undesirables' was to take them out to the forest in their hundreds and thousands have them shot by firing squad. A good book to read is Chris Brownings "Ordinary Men" about just such a German police battallion assigned to this duty. Browning discovered that most of the men did not really want to do such duty, but that the vast majority of them went along and did it anyway, mostly just to not be seen as shirkers or as someone who'd let down their comrades. Many of them were traumatized by it, and had to be utterly drunk to do it. Commanders found that these firing-squad units were often 'ruined' by the massacres, and had problems with depression, alcoholism, and general despair at their actions. The gas chamber was in a way meant to be more 'humane' for Nazi troops, in that only a small number of them would have to actually operate these machines (oftentimes operated by the death-camp inmates themselves).
The point is, is that the scariest thing about the Nazis is that they were just normal humans, and not monsters. The average rank and file soldier would (and did!) commit war crimes not out of a fervent bloodlust, but because it was simpler to conform. Ordinary people will follow orders, even terrible ones, as long as they perceive that these orders originate with an authority they respect.
If you'd like to read more, some books I may recommend on the topic:
Chris Browning's "Ordinary Men"
Goldhagen's "Hitler's Willing Executioners"