IMO, a true free market would not result in the majority of wealth concentrated at the top. The more wealth concentrated at the top the more monopolistic power the elite have and monopolies are in direct opposition to a free market.
I'd argue that a true free market inevitably ends in exactly that. The endgame of pure capitalism is a tiny group of people basically controlling everything. That's why we rein it in so that we can still reap as much benefit as possible without descending into oligarchy. At least, we used to.
I once listened to a talk where they listed all of the monopolies of the last hundred years or so and traced each one to artificial regulation in the market place. I suppose this alone doesn't prove that monopolies wouldn't exist without that regulation, but I haven't heard as compelling a rebuttal to this other than the intuitive assumption that capitalism creates massive inequality. I haven't really been presented with any real cases of this, though, because there has always been intervention to taint the sample. We haven't seen true free markets, we only understand how they function, not which specific results they produce, or how consistently they produce them. In this way, the thing that is good about free markets is that they function more predictably and openly than regulated inequality. Regulation, whether you prefer it or not, is much more messy and resource taxing.