There are so many people in America that democracy has indeed lost its significance. This is because the decisions of the government usually do not even affect individual people very much. For instance Obamacare is highly debated and argued about. It doesn't even affect me. The act of voting only matters if the vote can impact you depending on what you pick.
Democracy requires involvement of the entire country. I don't feel that the required level of involvement is present in modern America. I also believe that large corporations now control governments and voting is no longer a valid method of election. There is no way for an everyday person to voice their opinion in government.