Topher Hallquist effectively preaches cosmopolitanism to the Effective Altruism community:

Can you imagine a politician advocating free trade on the grounds
that, while it might hurt the politician’s own country a little, it
would have enormous benefits for people living in other countries? Or
making the same argument for immigration? In the United States, critics
of military intervention tend to focus on the costs in terms of American
lives and dollars, and the “lack of a compelling national interest.”
The fact that these interventions often wreak enormous havoc on the
countries we bomb and invade can seem to come in as a distant fourth in
anti-war rhetoric.

I suspect this also explains much of why most people aren’t more committed to fighting global poverty. People may
to believe, for example, that their donations will just get stolen by
corrupt governments, but often this sounds like an excuse. And imagine
what would happen if you went beyond praising the cost-effectiveness of
anti-malarial bed nets, and told them to direct efforts from specific local causes they support. In response, they probably wouldn’t
tell you they care about geographic neighbors more than foreigners, but
you might hear a little speech about the importance of responsibility
towards your own community.

Topher remarks that “it’s hard to explain America’s
current immigration policies without assuming a lot of quiet support”
for citizenism.  But he actually establishes a broader point: it’s hard to explain any country’s policies on any important issue without assuming a lot of quiet support for citizenism.  Indeed, silent citizenism is baked into countries’ very perceptions about what issues are important.