Nobody is talking about that america should save the whole world (to stay in your expample). But from my point of view your fellow citizen are your brothers and sisters, and you refuse to help them because you might help some non-americans with it too.
Thats sad.
P.S.
I dont fell bad for helping your brothers and sisters with my taxes / insurance payment
https://www.youtube.com/watch?v=Mwantba05Y0
Maybe thats the main diffrence between you and me.
For me Health care is a right, for you its a privilege