A main reason was Adolf Hitler and his obvious need for power and to dominate, he was a soldier in the First World War and never forgave Germany for surrendering, he wanted to make a Germany that didn’t surrender- he wanted to make Germany extremely powerful
Also I think another big contributor to Germany’s part in the war was the Treaty of Versailles which was made by the allies as a result of World War One for Germany to pay yearly reparations and this inevitably led to the Hyperinflation crisis in Germany in the year 1923 which left German people starving and penny less as Germany could not pay reparations for the year 1922 which led France invading the Ruhr- a large economic area for Germany which harvested most of the gold and iron reserves, after the Hyperinflation most people had lost everything and lost faith in the Weimar Republic and some Germans turned to more extreme parties, like the; national social Democratic Party (NAZI’s)
This is all I can contribute apologies I only know enough about Germany’s political part in WW2 and the making of it.
Hope this helps.
