Chuck Collins is a co-editor of Inequality.org at the Institute for Policy Studies and author of the book Born on Third Base. The opinions expressed in this commentary are his own.

When folks say that billionaires shouldn't exist, it's nothing personal. Some billionaires are nice enough. Some spend generously on philanthropy.

That all sounds great. But we don't need more do-gooder billionaires that give to charity — we need fewer billionaires.

The problem isn't really individuals making money. The problem is having an entire system that grows the wealth of billionaires at the expense of everything else we care about — including our democracy.

As the concentration of wealth in our country accelerates, an increasingly small sliver of the population enjoys an increasingly large say over how wealth and power are distributed. And make no mistake: Wealth is concentrating.

My colleagues and I found that, in 1990, the total wealth of all US billionaires was $118 billion in today's dollars. Last year, we found, it grew to over $3 trillion.