That person should grab themself by the ears & pull!
America has a very unique and diversified culture. We are a melting pot of everyone who wanted to become an American. Former immigrants brought and implemented bits and pieces of their cultures into the whole of America rather than clinging to their former homes singular culture. They were proud to become Americans, they did not want to "go home" because America was their home. They taught their children to speak only English and learn American ways rather than their former ways. They dressed as Americans, ate American food, bought American products, learned and celebrated American holidays. And yes, they fought for their freedom that they found in America. Because American culture's foundation is freedom.
You just have to look around you at the way of life for everyone in America versus other countries to see the differences in culture.