If you are a progressive, you tend to believe that we are moving towards a more equitable society, an open society that recognizes the rights of all. You tend to think that this is the inevitable arc of human progress. You actually see progress, and not just the churning wheel.
And over the last 30 or so years, you could point to progress on some key social fronts, women's rights, gay rights, minority rights. But at the same time there seems to be a fundamental inequality that underlies everything. Economic Inequality.
And that inequality undermines everything else. There is a new book, that is all the rage, "Capital in the 21st Century," and it seems this book lays out the case that inequality is inevitable in late stage capitalism.
So yes, the 99% vs the 1% is not a mirage. It's an inevitable state that unrolls as capitalism hurtles onward. It's natural and inevitable that wealth concentrates in fewer and fewer hands. Money makes money, and works for itself. And more and more people are left out in the cold.
And all that concentrated wealth skews our politics and our society. And the only way to reverse this a program of drastic measures with the goal of income redistribution. This smacks of "socialism," or "communism" or whatever, but without a political class working against income inequality at the root, we end up with a wealthy few lording over the unhealthy many. It's a flaw in capitalism...