"Wonder Woman" spoilers
Why? Well. Several reasons.
One. Right after Hitler ended his service in WWI and heard about the treaty, he was angry even then. But his immediate reaction was to serve as an officer in the socialist Bavarian Soviet Republic.
Hitler obviously wouldn't stick with that political model: he would sign on to the so-called "stab-in-the back legend", under which "traitors" such as Jews and Communists home undermined the war effort.
This legend was invented by Erich Ludendorff.
"Wonder Woman" spoilers
Hitler did not become famous until the Hitler-Ludendorff-Putsch. The event got him national attention, his subsequent trial allowed him to propound his by-then extremist views to the nation at large, and his cushy sentence -- quite possibly related to the involvement of "respectable" figures like Ludendorff -- enabled him to write Mein Kampf while in prison; his extensive visitation rights helped others like Rudolf Hess contribute to editing the eventual best seller.
"Wonder Woman" spoilers
The proceeds from Mein Kampf allowed Hitler to pay off his court costs. He made a great deal of money off the book (even more since he refused to pay taxes on the proceeds -- a debt that was waived once Hitler took political power.)
It was a success that convinced Hitler he could take power by legal means.
Three. However, the Nazi Party was nevertheless banned in 1924.
Who picked up their slack, merged his party with theirs and got them seats?
Yep it's Ludendorff again
"Wonder Woman" spoilers
Ludendorff eventually broke off his friendship with Hitler in 1925, but for personal rather than ideological reasons. And the breakup was somewhat one-sided as Hitler continued to look up to him.
Ludendorff really was so important to the rise of the Nazis that I find it inconceivable it could have happened without him. Even if WWII happened it couldn't have happened in the same way.
I'm deeply curious to see if the movieverse even bothers to patch this one up.
"Wonder Woman" spoilers
Final note. Wikipedia says the version of Ludendorff in the movie bears little resemblance to reality. To the extent that the real Ludendorff didn't have fuckin supernatural powers or Ares whispering in his ear that's true, but he was definitely an evil dick and imo would have taken this opportunity if presented it, most prominent Germans would not have done the same. If Ludendorff has any descendants around they can't really claim that this is slanderous.
"Wonder Woman" spoilers
He came up with the idea. He was the first prominent figure to use the phrase "stabbed in the back" in reference to the German war effort. And he continued flogging this during his later career in politics.
Two. That later career in politics kicked off with a series of attempted coups: he was involved in both the Kapp Putsch, stopped by massive civilian/worker resistance, and Hitler's Beer Hall Putsch. In German it's called the Hitler-Ludendorff-Putsch. I'm serious.