I've hammered this one home before. Of course, the few times I have gotten it through a liberal's head, they pause for a few minutes and then say "At least there wouldn't be any rich anymore." That's when I realized that their real goal, just as Ayn Rand pointed out, was the destruction of the wealthy. If we are all desperately poor together, they are fine with that. Think of how they romanticize third world nations and stinky hippies living in filth. Once you realize their goal is to reduce us all to pigs wallowing in the mud together, you realize there is no reasoning with people like this.
This reminds me of that video clip of Margaret Thatcher in front of the House of Commons where she says to one person (paraphrasing), "The situation of the poor has greatly improved under my tenure, just the same as the situation of the rich. Since you're complaining about the rich, it only proves to me that you don't care if the poor are poor, just so long as the rich are less rich."