It's a convenient target because the super-rich have never had as much wealth and power in the entire history of the U.S. as they do now. Inequality is worse now than it has ever been.
Consider an extreme hypothetical, where one person in a country has all the wealth, and everyone else has zero. That obviously cannot sustain a functional democracy. Now consider the other extreme, where everyone is mandated to have exactly the same amount as everyone else. Both are distpoian, but we are far closer to the former than the latter.