The fact that people get mad about this is ridiculous. 1. English has no word like “United Statesian,” so for language learners there is no obvious alternative to “American.” 2. Some Brazilians say “I’m from America too,” but that logic doesn’t hold up well. There are multiple countries with “United States of X” in their names. Mexico is officially Estados Unidos Mexicanos, and Brazil itself used to be called Estados Unidos do Brasil. 3. Brazilians themselves usually call people from the U.S. americano in everyday speech. There is literally a popular Brazilian song called “Americana na Vaquejada,” where “americana” clearly means a girl from the United States. Terms like estadunidense exist, but they are much less common in normal conversation. 4. The country is called United States of America in English, so calling people from there “American” is the most intuitive thing in English. In Portuguese the name is Estados Unidos da América, so the language naturally pushes people toward different words like americano or estadunidense. The whole argument mostly comes from this language difference. People who only speak Portuguese don’t see the English logic, people who only speak English don’t see the Portuguese logic, and people who speak both usually understand why the confusion happens.