The communist regime of USSR led by Gorbachev was no longer willing to intervene in the eastern countries, in a time that the countries were facing increasing pressure for freedom and liberties. The success of some early uprising in countries like Hungary endeared other countries to follow suit.
The gravity of Jupiter helps the comets from hitting the earth
Answer;
Nationalism convinced the people of Europe that their own nation could take on any military threat. This was a role nationalism played in the outbreak of world War I.
Explanation;
Nationalism reached a fevered pitch in Europe prior to the first World War. As a political tool, it was the belief that European technological, cultural, economic and military superiority was the cause for the subjugation of more backward economies and cultures.
The pan-Slavic nationalism inspired the assassination of Archduke Franz Ferdinand in Sarajevo in June 1914, an event that led directly to the outbreak of World War I.
So all the power isnt in one persons hands, and because if checks and balances werent here one person would hold all the power which would be bad :)
