Hitler's experience being homeless in Vienna influenced his antisemitic views, but just to be clear, he was homeless prior to WWI.

After the war he was sent by his military superiors to spy on a German Workers party in 1919, and the leader of the party, Anton Drexler, ended up taking Hitler under his wing. Hitler eventually took over the movement that begun under Drexler, before turning it into the Nazi party. At one point, Hitler threatened to abandon the party unless Drexler handed over complete leadership.

Drexler remained a party member in name only, and seemed to basically serve as a propaganda tool to help retain pre-nazi membership. For some odd reason Hitler even ended up adopting Drexler's unique little mustache.

https://www.ebsco.com/research-starters/history/adolf-hitler

https://en.wikipedia.org/wiki/Anton_Drexler#CITEREFEvans2003

So after WWI an already antisemitic Hitler with a reputation in the army as unfit to lead due to psychotic tendencies, felt strongly that Germany had been greatly betrayed. But so did the military superiors who first sent Hitler to spy on Drexler and the Workers party, before eventually ordering him to join the party's leadership when Drexler took an interest.

Despite his experience in Vienna homeless shelters influencing his antisemitic views, Hitler's superior, and head of German Intelligence's "Education and Propaganda Department," Karl Meyer, was allegedly the person who first instructed Hitler to write about those views.

As the Nazi party grew, it seems a bit unclear when (if?) Hitler's superiors stopped providing him with official commands/communications, but Meyer would later state that he had been instructed by General Erich Ludendorff to have Hitler join the workers party.

Ludendorff oversaw virtually all decisions regarding Germany's strategy and war effort until the country's defeat in 1918. Later during the years of the Weimar Republic, he took part in the failed 1920 Kapp Putsch and Adolf Hitler's 1923 Beer Hall Putsch, thereby contributing significantly to the Nazis' rise to power.

After the war, Ludendorff became a prominent nationalist leader and a promoter of the stab-in-the-back myth, which posited that Germany's defeat and the settlement reached at Versailles were the result of a treasonous conspiracy by Marxists, Freemasons and Jews. He also took part in the failed 1920 Kapp Putsch and 1923 Beer Hall Putsch before unsuccessfully standing in the 1925 election for president. Thereafter, he retired from politics and devoted his final years to the study of military theory. His most famous work in this field was The Total War, where he argued that a nation's entire physical and moral resources should remain forever poised for mobilization because peace was merely an interval in a never-ending chain of wars. Following his death from liver cancer in Munich in 1937, Ludendorff was given—against his explicit wishes—a state funeral organized and attended by Hitler.

TLDR: Is there a chance preventing a German economic crash also could have prevented a Hitler situation/WWII? That's difficult to say.

I don't think the USA just forgot about it, ISIS was never a real issue, just a anther cause for endless proxy wars, it's a machine that works as intended.

"Nation building" after WWII wasn't free or benevolent at all (USA or USSR), the tactic was to control the nations instead of letting them regain full independence - as much as/in a form a post-British-empire world can allow imperialism.
(Israel was a form/consequence of this 'nation building' as well.)

Well, not as if Republicans allow taxpayer dollars to be used to help citizens domestically anyway.

They actually do. For billionaire citizens.