>>215891721 (OP)
It's complicated but essentially post WWI the German economy became increasingly reliant on the US economy for its continued growth. US investments were necessary to maintain growth in nearly all sectors of the economy. This wasn't an issue at first because the US was seen as economically prosperous, having vastly benefited from the war and it allowed Germany to quickly regain stability.
This is why the 1929 crash was so spectacularly damaging for Germany, much more so than in the UK or France.
Combine that with an unstable society that suffered greatly during WWI and was in the midst of division between militarist conservatives and socialists and there was plenty of resentment for extremists to benefit from. The nazis took advantage of the situation by massively amping up public spending, preparing for rearmament by spending what little reserves the late Weimar republic had built to reestablish a stable economy. They also gave IOUs in the form of MEFO bills, meaning Germany at that point was essentially a ticking time bomb tethering on the edge of an even bigger economic crash. The Anschluss and later annexation of Czechoslovakia helped by injecting fresh gold reserves but by 1939 Germany was essentially broke and had to go to war to not only stave off economic collapse but also secure food supplies because the collectivization of German farms had failed and the country was still in a net deficit of food
tldr the nazis were opportunists who burned the candle on both ends and went on a war of conquest to prevent their complete collapse.