Sure, the Democratic Party is captured by corporate interests. It is the only way to stay in the game. Lots of sincere people involved would like for it to better represent actual people. But politics is called "the art of the possible" for reasons.

95+% of Americans are underclass. (Between 1945 and ~1975 there was a pretty strong middle class. By 1990 it was gone.) Of those of them who vote, about half vote for each party. The rest, who knows?