After World War I, why did democracy survive in some countries and not in others?

The aftermath of World War I involved momentous political, cultural, economic, and social change across the world. Political transformation occurred in most of the principal parties involved in the conflict; Germany, Great Britain, and Turkey all became electoral democracies between 1919 and 1923.
However, that is not to say that each of these democratic systems survived. After Germany signed the Treaty of Versailles in 1919, adopting democracy through a constitution and free elections, Adolf Hitler and the Nazi party gained control only fourteen years later. The Treaty of Versailles was based on assigning blame for the war to Germany, which was never accepted by German nationalists. The transition from Germany's brief democratic system to that of totalitarian Nazism is associated with support of nationalism over globalization; the Nazis' use of violence to influence the public, even while elections continued; and public dissatisfaction over economic circumstances associated with war reparations. Anti-Semitism was a large part of what would become Hitler's devastating campaign of genocide during World War II, but I am referring to the period leading up to this conflict, before the Nazi party put forth the "Final Solution."
Great Britain's electoral democracy has continued since World War I and, in fact, had been shifting toward democracy since the Industrial Revolution. The Industrial Revolution caused aristocratic influence to decline and population to increasingly become concentrated in urban areas. Urbanization resulted in a new middle class, which desired fair wages and working conditions. As a result, the middle class wanted fairness and equity in elections, improved representation in government, and parliamentary accountability to the public. After World War I, there was an increase in both male and female suffrage. Men opposed residence qualifications of voting and believed they should be entitled to vote, as they had served their country; women also believed they should have the power to vote, as they had served their country too.
Interestingly, Turkey was the only power during World War I to change the terms of its defeat and negotiate with the Allies as an equal. Turkey was originally part of the Ottoman Empire, which collapsed after the armistice was signed in 1918. According to the conditions of the armistice, Turkey as a nation was to be eliminated, with the exception of a small region. A Turkish national movement was established, leading to the creation of an independent, sovereign state. The 1923 Turkish general election established a republic; to this day, its constitution declares, "the Republic of Turkey is a democratic, secular and social state." While nationalism was linked to Germany's rejection of democracy, for Turkey, nationalism was a catalyst for this form of government.
America's role in World War I is also linked to democracy. President Woodrow Wilson not only promised that it would be a "war to end all wars" but that the war would "make the world safe for democracy." American democracy had already been established through its Constitution, though universal suffrage was achieved after the war. Similarly, Canada became a democratic country when the provinces of Ontario, Quebec, New Brunswick and Nova Scotia joined together in 1867, while universal suffrage came later. For these countries, democracy evolved before and after World War I, as a continuation of ideals that are comparable to those previously discussed in relation Great Britain.
World War I can be seen as a conflict that saved democracy—but it would take another three decades and an even more devastating war to consolidate democratic institutions and establish the peace that the treaty of Versailles initially sought to achieve.