I do not see what the 50% threshold has to do with anything, nor why the idea of not sacrificing for the whole unless everyone else is sacrificing is a fallacy.

If US makes it so its residents cannot afford to go to Hawaii and Taihiti and Seychelles for their honeymoon, but China continues to allow their residents to go, then unless the people of the US are very selfless, I predict it is not going to well for the leaders of the US.

It is a prisoner’s dilemma, if anything.