There is a strong argument to be made that Western Europe was shaped by its competitive nature, as numerous smaller states competed with one another in a struggle for supremacy.

This is most clearly shown in the long history of wars running across European History. The frequent clashes and fighting between European States drove military innovation. As the scale of warfare increased, so too did the pressures it placed upon State administration, and thus we see the rise of more centralized forms of government, as represented by the Absolutist State.

But warfare is only part of that story. We can talk about economics as well. The theory of mercantilism is predicated and dominated by a deeply competitive vision of politics. It is based on the assumption that various political states are in a competitive zero-sum game, where one country's loss is another's game. We can also speak about the rise of industrialization, which began in England and spread through Western Europe.

We can even talk about culture and the ways in which different courts and monarchies have patronized the great thinkers and artists of their countries, as well as those of other countries, in order to advance their reputations in Europe. European states have had a long history of the patronage of artists, musicians, composers, philosophers, scientists, and poets, creating a competitive dynamic.

One answer to this, at least, is that the multiple competing states allowed European civilization to flourish and to become powerful.  This idea is proposed by, among others, Niall Ferguson in his Civilization: The West and the Rest.  

According to this theory, competition brought out the best in these states.  It forced them, for example, to keep up with one another in terms of the best ways to fight wars or to finance governments.  If one of these states failed to adopt some advance in technology or organization, it could be overtaken by other states.  This gave every state the incentive to push ahead as much as it could.  This competition, then, made European civilization the most powerful in the world.