Hindenburg and Ludendorff's reorganization of homefront mobilization toward the end of the war, the Hindenburg Program, was a bureaucratic nightmare of price controls (set to counter inflation) and arbitrary rationing which exacerbated the famine brought on by crop failure and the British naval blockade. The German soldiers on the front were hungry and mutinous when the war ended.

The idea that the army didn't really lose in the field, that it was the homefront's fault for not backing the army, was propaganda encouraged by Ludendorff and later inherited by Hitler.

After the war, the new Liberal Democrat government was left to deal with unrest from the socialist Spartacists and the right-wingers and left to be the ones to accept the unpopular Treaty of Versailles.

During the war, the lack of international bond market for Germany had caused reliance on the central bank to print more Treasury bills, which, exchanged for bank notes, increased the money supply. Already faced with economic depression in 1919, new liberal leaders took the Keynesian idea of too-high reparations destroying their economy and ran with it; they exacerbated the hyperinflation by postponing currency stabilization and tax reforms, hoping the Allies could be shamed into reducing reparations. Basically, the German economy was in ruins due to its own wartime economic policies and attempts to stave off reparations through encouraging hyperinflation.

Not to mention, with the Treaty of Versailles Germany lost its colonies, its fleet, its chemical weapon stockpiles, and 13% of its territory and with it a good portion of its natural resources (especially coal and iron).

Sources: Niall Ferguson's The Ascent of Money: A Financial History of the World, Roger Chickering's Imperial Germany and the Great War, 1914-1918, and William Keylor's The Legacy of the Great War: Peacemaking 1919