I disagree with this completely, because I don't think it's true at all. A free market is the most anti-monopoly system you can possibly have. Monopolies are created and maintained by regulations which create high barriers to entry for new companies. I know it's probably getting a bit boring but here's (yet another) video of Milton Friedman debating this exact point.
[video=youtube;tdLBzfFGFQU]http://www.youtube.com/watch?v=tdLBzfFGFQU[/video]
It isn't getting boring at all. The whole point of politics is debate and disagreement, and the present system of two parties with almost the exact same views on every issue parading as the 'right' and the 'left' is an anti-thesis of everything representative democracy and the right to choice stand for. A point, incidentally, I suspect you would be in agreement with. But nonetheless, Friedman points out two examples (the New York Stock Exchange and the De Beers diamond companies) that do exercise monopolistic dominance over the markets, but goes on to assert that they are the exceptions to the rule of free markets breaking down monopolies. But today, what do you see but giant monopolies across entire industrial sectors where government regulation is slim to non-existent? Take the electronic gaming industry, for example, an industry I follow closely due to my dabbles with its products. Since it became a fully-fledged 'industry' in the aftermath of the web bubble, as opposed to just a niche market, one company (Electronic Arts) has aggressively expanded and bought out other publishers, established games licenses and dozens of development studios, creating a near-total monopoly on brand names, publishing opportunities and development talent within the PC sector. Fifa, Mass Effect, Battlefield, Medal of Honor, Need for Speed, Simcity....all very popular gaming franchises, all now owned by EA. The best studios (Bioware, Dice, et al) have also been absorbed. And having established its monopoly, EA are now attempting to extract ever greater revenues from it, charging players for micro-transacations (dollar ninety-nine for virtual purple helmets, for example) within the games themselves because they know that the marketing revenue they put into the game means that 99 percent of people will buy and play it without bothering to note its quality, affordability or replayability, thus obviating the need for anything other than extremely quick game turnover times, a lack of attention to detail and hastily-made 'social' gameplay. Their monopoly is near-absolute (save for Valve (Half-life), Activision(Call of Duty) and a few other upstarts), and is driving smaller publishers to emulate their business practises or die, and is driving indie game developers to crowd-funding on Kickstarter to find the money to make games. There is next to no government regulation on the PC gaming industry, yet the existence of a proto-monopoly like EA seems to disprove Friedman to some extent.
Another example would be Google. Internet laws are still in their infancy (most law-makers are likely still firm pager adherents), and abuses of the system (As evidenced by the spate of recent Google privacy-related lawsuits) are common, thus making the internet a relatively free market. In this free market, we see Google, a truly titanic behemoth, the world's largest search engine, which also owns the world's most visited video website (Youtube), and a swathe of subsidiaries in fields ranging from online maps to books reviews to stores to news websites to e-books. At the same time, we see privacy intrusions, data collection for advertising purposes, and search-pattern tracking, all illegal under traditional law, becoming rife across Google's sites and its web-browser, Chrome. Yet people still keep using Google because there is no alternative. What do we use to search for things? Google. To the point where 'let's google it' is now a universally-accepted phrase. Yahoo will give us one tenth of the answers google does, MSN even less. The one competitor who could give Google a run for its money in holding the world's interest was Youtube, which....was bought by Google.
Friedman (and your average free-market proponent) argues that if a monopolistic company slacks off, another one will rise to take its place at no cost to the consumer. But what he does not consider is that companies have now grown so large off supposedly 'temporary' monopolies that they have the ability to simply buy out aspiring or innovative competitors, and have the means to obliterate them via mass media and smear campaigns if they don't consent to being bought out. Ea bought out most of its competitors. Google bought out one of its biggest rivals. The list of monopolistic companies running smear and misinformation campaigns against their smaller rivals is long and disheartening.
The age where companies could be trusted to act in the spirit of the free-market is long, long gone. Profit now outweighs everything else: the quality of the product, the importance of happy labor, the benefits of anchoring within a local community, etcetera. And advertising and marketing are now the standard ways to get us gullible consumers to perpetuate monopolies even after we grow tired of the products they produce. And it is here that monopolies in the free market derive their persistence from; marketing.
An informed consumer alone cannot stand against billion-dollar marketing campaigns that target everyone around him/her and persuade them to buy crap. The free-market myth of consumer choice is just that; a ridiculous myth.