I’ve encountered the argument for Estadounidense from Mexicans, but it falls apart when you counter that the name of their country is Estados Unidos Mexicanos.
If you’re really feeling like putting the screws to them, point out that while all of the USA is America, Mexico Valley is a very small part of the territory of their country, and is itself named after the Mexica people that inhabit it. So rather than translate Estados Unidos Mexicanos as the United Mexican States, it would more accurately be the United States of the Mexica Empire.
Then you can ask them if they’re Mexica, or from one of the conquered territories.
I’ve encountered the argument for Estadounidense from Mexicans, but it falls apart when you counter that the name of their country is Estados Unidos Mexicanos.
If you’re really feeling like putting the screws to them, point out that while all of the USA is America, Mexico Valley is a very small part of the territory of their country, and is itself named after the Mexica people that inhabit it. So rather than translate Estados Unidos Mexicanos as the United Mexican States, it would more accurately be the United States of the Mexica Empire.
Then you can ask them if they’re Mexica, or from one of the conquered territories.