A simple and straightforward question. Why in the world would any trading setup/edge/ pattern/ rule work? It does not matter if it is a systematic or discretionary method. The very logical expectation is that if there is any trading setup that really has a positive expectancy and can give a trading edge, then sooner or later it should be exploited and arbitraged away by other traders. This does not apply to value investing since you can really find undervalued companies despite massive effort exerted by other investors/ traders to make a advantage of every piece of information they can find. It is just the way the market works. But in the world of technical trading, pretty much every trading approach you come up with is already known by others i.e., there is nothing new here. So why do you think you have a trading edge over the market when so many others can do exactly the same as you do and even with much greater capital available to them.