As I have mentioned before, we cannot make the same sort of money out of permanent ownership of controlled businesses that can be made from buying and reselling such businesses, or from skilled investment in marketable securities. Nevertheless, they offer a pleasant long term form of activity (when conducted in conjunction with high grade, able people) at satisfactory rates of return.
Observing that the market was FREQUENTLY efficient, EMT Adherents went on to conclude incorrectly that it was ALWAYS efficient. The difference between these propositions is night and day.
In my opinion, the entire field of investment management, involving hundreds of billions of dollars, would be more satisfactorily conducted if everyone had a good yardstick for measurement of ability and sensibly applied it.
You have to turn over a lot of rocks to find those little anomalies. You have to find the companies that are off the map - way off the map. You may find local companies that have nothing wrong with them at all. A company that I found, Western Insurance Securities, was trading for $3/share when it was earning $20/share!! I tried to buy up as much of it as possible. No one will tell you about these businesses. You have to find them.
In some corner of the world they are probably still holding regular meetings of the Flat Earth Society. We derive no comfort because important people, vocal people, or great numbers of people agree with us. Nor do we derive comfort if they don't.