Is Marx's idea of capitalism accurate?

This week in class we had our symposium on Friedrich Nietzsche, Karl Marx, and Jean Paul Sartre.  All three of these philosophers have very opposing views on how society works and interacts with each other.  Nietzsche expects strong people to express their strength in every way, however this promotes a society that doesn't get along with each other very well.  Sartre is very unsympathetic in that he believes even if people think that they are stuck in a bad situation that they can't do anything about, they ultimately have the freedom to leave.  If they don't leave, then it is their responsibility for keeping themselves in the bad situation.  Marx believes that capitalism results in only two classes: the super rich and the super poor.  He also thinks that the poor class (the proletariat) cannot ever get out of their situation unless their is a revolution of the entire class.  

According to Google, the United States is in the top 5 most capitalistic countries in the world.  However, what marks says about capitalistic societies is not true here.  First of all, there are more than just 2 classes.  An extremely small percent of the population is extremely rich such as celebrities, famous athletes, CEO's of large companies (Google, Microsoft, Facebook), etc.  A larger portion of the population is very well off such as doctors, lawyers, etc.  Then there is the percent of the population that are teachers, social workers, etc. that make enough money to have a good life, but still might live paycheck to paycheck depending on their family size.  And lastly, there is a large percent of the population that survives on minimum wage jobs, not being able to afford the same type of lifestyle as the other classes.  Marx makes it seem like capitalistic countries are very extreme, but in America it is clear that this is not the case.