The apparent message of the entire piece is "Want to be upper class? Just start a business!" without any notion of either (a) how the average person could do so

The apparent message of the entire piece is "Want to be upper class? Just start a business!" without any notion of either (a) how the average person could do so or (b) how we could begin to change our society/culture in a way to facilitate the average person being able to do so. Result: it comes across as something you believe everyone should be able to do as is. Also, be very careful about sentences like "The middle class has a culture of spending most money as soon as you earn it." There are certainly parts of the middle class that are like this. We all know the concept of keeping up with the Joneses and overextending credit in an attempt to do so. However, there are also large parts of the middle class (and, again, the lower class you so ignore) where it's not "culture" it's "necessity". Sure, maybe some could survive on 20% less but at the cost of things you might take for granted--living in a safe neighborhood, eating healthy food, or having health insurance. But, no, surely it's just a culture of unnecessary spending. It may not have been your intended message, but it's certainly the one that comes across.