An Average Joe View On Universalism
You may ask yourself why should we bother with universalism. We live our more (or less) comfortable lives. We work or study, raise a family, pay our taxes, perform our civic duties (in my country, these includes serving in the army), and we are content.
Why should we bother with the welfare of people living thousands of kilometers away? What do we care about the pollution in some far away country?
The simple truth is that in today's world, everything that happens on this planet may affect us or our children. We cannot remain indifferent to what happens half a globe away from home. We should always consider the ricochetes that may affect us.
Yes, the universalism is first of all about such terms you hear in management courses: global optimization, synergy rather than local optimizaion, which is mostly what we see today. Each group of people trying to optimize their position (local optimization) and the hell with everyone else. As long they can get away with it, of course.
If they are a weaker group than others, then their actions may provoke intervention by stonger entities (like other countries or the central government of the country where they reside, etc') that will counteract their attempts.
There are many examples for it:
The wars in the balkan during the 1990's. The serbs tried to improve their situation at the expanse of the Muslims (Bosnia, Kosovo). However, stronger powers intervened and their attempts were counteracted.
Iraq took Kuwait in 1990 in order to annex their oil wells with a lame excuse that Kuwait used to be an Iraqi province. This move was counteracted by a coalition of nations that drove the Iraqis back home.
The USA invaded Iraq despite opposition from many other countries and from a vast number individuals all over the world.
(I don't want to get here to the issue of whether their move was right or wrong, whether it was wise or stupid. My point is that the USA affords itself to play whatever game it wants despite loud protests).
These examples involved acts of aggression of one country or group of people against another country or group of people. However, acts of self interest may involve many other actions. For example, pollution created by one country that affects its neighbours (or by a plant in a country that affects surrounding communities).