I have a simple idea about so called edge deterioration, I will try to explain it in this post. It's understood that trading edges deteriorate over longer run. This is said to happen due to the fact that too much trading capital is thrown to exploit the edge (i.e. too many people start to spot and use that edge). Then the market changes (adapts), it's said it becomes "more efficient" and the edge is no longer profitable. Here's a simple thought experiment: if edge becomes unprofitable, people exploiting it start losing money and abandon that edge (or lose everything), right? So what we get is the process where less and less trading capital is thrown to exploit the edge - an opposite of what was described in above paragraph. Following this logic, the unexploited edge should become profitable again. Is this true? Does this "edge cycle" exist in the markets?