Because the rest of the world is fed up of Americans claiming they are xyz nationality when in reality

1. they've never set foot in that country
2. they know nothing of current politics in that country
3. they know nothing of the current struggles in that country
4. their only connection to the country is some arbitrary fact like "i like a song from an artist from that country"

You're just an ignorant American who has nationality dysphoria.

Maybe if you stand in a garage you can convince yourself you're a car? Try drinking only petrol coloured beverages to really convince yourself.