In the US, we don't have any other social stratifications that would justify your response. Typically when we speak of class in the US we are talking exclusively about economic class. The problem with your argument is that our democratic institutions aren't fine. (Sure, sure Representative Republic). For instance in nearly every single state we have a group of people that are underrepresented by their electorate. In blue states it's typically conservative viewpoints and in red states it's liberal voices. Because of gerrymandering, in some cases unlawful, we've lost most of our moderate representatives that have led to the gridlock and partisanship we have today.
Proportional voting or a move to a parliamentary type of electorate would help these issues and allow for more voices to be heard. There's also the fact that more populous states have less representation in the House than do less populous states due to the limits imposed on the number of Representatives due to space requirements. This is problematic. Add to that the Citizen's United verdict that lifted campaign contribution limits on corporations while still enforcing them on individuals and I think I've made my point that our Democracy is in trouble without even touching the malfeasance by the actual political actors of either party.
The real problem though is that the middle class, the foundational aspect of a functional democratic process is being hollowed out.
When you look at the fact that money is considered speech and the top .001 of the US makes as much every year as the bottom 80% of the country there is no way that even the amalgamated voices of the bottom 80% could hope to have the same political sway as those with money and this divide is only getting worse.
Education is a poor classification of Americans, except for the fact that it generally correlates that the higher education you achieve the more likely you are to have higher income. Obviously your position of negative value degrees are the exception, however I'd be less likely to think that the wealthy are getting these poor degrees as are the poor. The wealthy can just write/ghost write their books and have them immediately be New York Times bestsellers without a single person other than themselves buying the book.In fact this is a common trick. The poor are generally less educated than the wealthy and this leads to an information imbalance that would prevent people from going into poor degrees instead of fields in demand like nursing, math, computer science, etc.
I'm sure many people on this board know someone stuck in a poorly paid IT helpdesk job because they got a Bachelors in IT or something else that didn't lead to money.