I doubt that technical analysis is the main reason for us to become successful in trading, its not true and wrong belief also. But it could could be one of the reason for us to get profit, because not all traders who became successful they technical analysis only, of course not.
indeed besides that there are other supporting factors, such as psychological. with psychologically well-established, it will certainly train us to discipline the analysis, so that the target is reached, even though it is faced with large fluctuations