The US is more accurately a corporatocracy, not a democracy
The idea of corporatocracy is that a country is run by, and for the good of, corporations as a whole rather than individual citizens. People who believe this view will point to things like the huge lobbying power of corporate interests, the level of influence of the corporate media, the fact that an awful lot of lawmakers have very close links with companies in industries that they are drafting regulations about, or the the bailout of banks etc.
You may or may not agree with whether this is really happening in the US or elsewhere, or the level to which it undermines democracy, but it helps to talk about what the word actually means rather than a straw-man argument.