The period that immediately followed World War I was marked by the fall of the German, Russian, Austro-Hungarian and Ottoman Empires. Basically, the governments were gone, and the people were left in total desolation. Economically, many people were ruined because wars are expensive, wars destroy workplaces, and war leaves many soldiers unemployed after the fact.
Democracy failed in the post-World War I world mainly because it was unable to allow for economic viability. It was impossible for everyone to have a say in the government of the countries, and establish some sort of economy that would keep people from star