Technical analysis is not intended to be anywhere near 100% accurate in predicting price movements. Rather, the goal is to produce predictions of price direction and magnitude such that large gains from the relatively few correct predictions are more than enough to offset the many smaller losses from incorrect predictions, leading to a positive return in the long run through proper risk control and money management.
Despite all the fancy and exotic tools it employs, technical analysis really just studies supply and demand in a market in an attempt to determine what direction, or trend, will continue in the future. In other words, technical analysis attempts to understand the emotions in the market by studying the market itself, as opposed to its components. If you understand the benefits and limitations of technical analysis, it can give you a new set of tools or skills that will enable you to be a better trader or investor.