Why did Wilsonianism fail at the Paris Peace Conference in 1919?

Woodrow Wilson was idealistic from the beginning of World
War I; in fact he had proposed his famous Fourteen Points before the U.S. entered the
war. Among the points was his call for the creation of a League of Nations which
hopefully would solve diplomatic issues and possibly even eliminate the need for a war.
This was one of several reasons that Wilson referred to the war as the "war to end all
wars." Wilson, however failed to consider the practicalities of European diplomacy.
France had previously been invaded (and humiliated) by Germany during the
Franco-Prussian War; in fact the German chancellor Otto von Bismarck had arranged for
the coronation of the first German chancellor at Versailles, thereby adding insult to
injury. Although revenge was certainly a motive as the above answer implies, it was not
the primary consideration. Rather, France hoped to cripple Germany and prevent yet
another invasion. It was this consideration that devolved into the famous War Guilt
Clause and reparations clause. There was no "reward" intended, only costs of the war,
although they were calculated down to the pension of the last French soldier. The French
representative to the Peace Conference, Georges Clemenceau, took a dim view of Wilson's
idealism. He  once commented:

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God gave us the Ten Commandments, and we broke
them. Wilson gave us the Fourteen Points. We shall
see.

 Wilson originally
objected to Clemenceau's demands; but soon learned that unless he acceded, Clemenceau
would not agree to his call for a League of Nations. He was so intent on creating his
beloved League that he agreed to all of Clemenceau's
demands.

As far as Japan, as noted in the above post, Japan
had entered the war anticipating that it would gain German possessions in Asia. Japan
left the conference empty handed, as did Ho Chi Minh, representative of the Vietnamese
People whom Wilson had unceremoniously thrown out. The failure of the conference to deal
with Japanese demands was a factor in Japanese Imperialism which led to World War II.
Similarly, by acceding to Clemenceau's demands that Germany be crippled, Wilson
inadvertantly gave a platform to Adolf Hitler who attacked the treaty as unfair to
Germany. His attacks were a major factor in his accession to power. Similarly, his high
handed treatment of Ho Chi Minh may well have been a factor in the advent of the War in
Vietnam fifty years later.