[madmask]

As fas as I know the more people use the strategy the worse it performs, the market is not static, it adapts. Other people react to the buy/sell of your strategy and try to exploit the new pattern.

[JonChesterfield]

This is an interesting observation in combination with the popular pension strategy to continually buy index funds regardless of performance.

[ericjmorey]

The average return from index funds is the benchmark that all those others are trying to beat but all the competitors trying to beat the average have a tendency to push successful strategies towards the average.

[bossyTeacher]

It only works until most people do it