I'm an American and I completely agree, but I think some context might be useful. Americans are trained from a young age that you have to sell yourself. You need to toot your own horn because no one else will. It is a component of the hustler culture in America. You always need to be fighting for the smallest advantage and overselling is a popular mechanism. Its incredibly dehumanizing, but thats never stopped America before.
Thank you. As a European who has spent a lot of time in America (and is married to an American, even), I appreciate you recognising and articulating this.