Something that is widely ignored in the USA is that "America" is the name officially given to the continent in 1507 by German cartographer Martin Waldeesmüller when the first official map showing the new continent was printed. In actuality, "America" only and exclusively applied to southern America. From then on, the inhabitants of the newly discovered continent were refered to as "Americans". Much later, the central and northern hemisphere were included in the concept of America.

This is why you will most likely start a fight in Ameirca, because the terms "America" and "American" were never used to mean "USA" and "US citizen", so obvioulsy it feels like an unfair appropriation of terms that have defined millions of people for longer than the existence of the USA. The USA lives in some sort of isolated bubble from the rest of America and that is why it is widely ignored this piece of history in the USA. No country has the right to appropriate terms that define millions of people equally.

Many educated people in the USA have acknowledged this problem and have come up with proper demonyms to exclusively mean "US citizen" such as United Statesian, Usanian or Usonian. Some online dictionaries allow the use of "United Statesian" although Usanian also sounds like a good demonym because it is even more distinctive and shorter if you want one short.

Until the USA gets its proper official demonym this will to come to an end.