Imagine three companies dominate a given market. In most geographies, say 75%, the two larger companies company with each other and a few other stragglers. But in 25% geography a single company dominates. Who is the problem? The larger companies, competing in their broader market or the smaller company?

As an example, Amazon is dominant in the online retail sphere. The have an incredible market share. But I've never once had this create a significant problem as a consumer. Why? Because the cost to me as a consumer to use something else is tremendously low. I can use Walmart.com which has gotten quite good. Or I can go to a physical store.

Meanwhile, people must tolerate anything Comcast pulls, though they certainly have a smaller share of the personal internet service provision market than Amazon does of the eretail marlet.

To me monopoly is not dangerous because of marketshare. It's dangerous when the bulk of its customers cannot switch to another service. Particularly so if the market is difficult for new competition to enter.

I get all the open internet gripes about Google and what they've done with Chrome. And that thing could become a monster. But the reality is that you can switch today with minimal impact to an excellent alternative browser.

People buying a drug like HUMIRA are not so lucky.