Over the past 25 years, our economy has not benefited lower and middle income Americans anywhere near as much as it has the wealthiest of us. For some reason, though, much of middle America continues to support the Republican party, despite the fact that we've been really bad at making sure our economy benefits everyone who's willing to work hard. Why? Because our party has used cultural themes-- religion, Second Amendment rights, etc.-- to distract voters into thinking that Democrats are necessarily anti-American.
There is nothing un-American about a presidential candidate telling a roomful of people on the coast that our economy hasn't helped working people in middle America. There is nothing un-American with pointing out that the Republican Party has been successful in exploiting cultural themes. For the record, there's also nothing un-American with being wealthy, nothing un-American with contributing money to a political candidate, and there is nothing un-American with having a frank discussion about the plight of working class people in our country.
When was the last time a Republican candidate spoke to a private gathering of wealthy Americans about the economic plight of our small towns? It probably hasn't happened over the last 25 years.