People, in general, like to be associated with success. We see it in a wide variety of fields:
Sport is about winners (and losers). When Canada wins more gold medals at the Winter Olympics than any nation previously, that forms an association between Canada and success. It applies, too, in league sports, where people will support teams that they perceive as likely to succeed.
But, equally, we can associate ourselves with success in many other ways--economic performance, human development, social policy, health indicators--indeed on just about any basis where we can compare ourselves to any other identifiable group of people.
Even in fairly mundane matters, the perception of success is important. When fundraising, potential donors respond much better to, "Your donation will help us continue our success," than to, "The Government has cut our funding and we will have to shut our doors without your help!" When shopping, consumers will be influenced by brand. Even where price is their most important criterion, brand will enter into the calculation, because of a perceived value represented by the quality of the product.
This sort of tribalism is not limited to nationality, either. Why do so many Aspies try to point to historical figures and fictional characters who share our traits? Because it gives a feeling a validation.
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--James