So you agree that merit and fairness have nothing to do with the ever-growing gap. That's a good start.
The voters base their decisions on the information they have, and the bulk of that information is controlled by a tiny minority of the population. It's not just the overt campaign ads, it's also newspapers, magazines, television, radio, major news sites on the web—you name it. Independent blogs are great but they're not an adequate substitute for professional journalism. For one thing, it's hard for a tiny self-financed blog to hire a full-time political correspondent in D.C. or send an investigative reporter to the Ukraine for six months.
Just because Warren Buffett has different opinions from the Koch brothers doesn't mean that either one represents or understands the needs of the poor.
Money is a measure of an individual's power to shape their own environment or exchange for the services of other human beings. When one person makes two or ten or a thousand times as much money as his peers, that is an important measure of how much influence he has in society. If one incredibly rich individual controlled 51% of the world's stock then we wouldn't have a "free market" or "free society" even if everyone else had personal gold-plated hover cars.