Some monopolies that appear out of natural progression of events are potentially more insidious. Their growth goes unnoticed and their roots go even deeper. 
Of course 'natural progression' also contains the human element within it. Meaning that an opportunity wouldn't always be available and empty slots will eventually be filled by people. If the occurrence of these events is such that players are organically coming from the same source then perhaps it might be called a natural monopoly. (This definition sounded a lot better in my head)

I have always believed that if something becomes to popular then it is usually time to move on. This thinking in me comes from an innovators perspective where an idea that was new at night would be old by morning - get it patented now or go home. But I found that this mindset helped me beat the bigger players on my own little chessboard.