The fall of the Soviet Union in 1991 was not a victory for the West. It was a defeat. The ruling ideology in the Soviet Union was communism, which is a western doctrine—communism was developed by the western intellectuals in Germany, England, and France. In Asian countries (where the first experiments in communism were conducted) most people were clueless about communism.
Through the communist regime in the Soviet Union, western intellectualism was controlling a major chunk of humanity—in the Soviet states, China, South Asia, and parts of the Middle East, South America, and Africa. The fall of the Soviet Union had a domino effect and one by one the communist regimes in most parts of the world collapsed. The traditionalist, regionalist, racial, and theocratic political forces are the beneficiaries of communism’s fall—in last three decades, such forces have acquired total political power in the post-communist world.
By defeating the Soviet Union, Reagan and Thatcher did not strengthen the West—they paved way for its decline.