You are right. To analyze price movements, it is necessary to historical data and graphs. The accuracy of analysis is not entirely valid, but at least close to the real price. For short-term investments, technical analysis is the basic foundation for getting started. My simple analogy, technical analysis is our preparation and equipment before camping on a mountain. If we don't have enough equipment such as clothing, flashlight, or food, then we will be constrained and uncomfortable in camping.
Same as in this case if we don't know about technical analysis, we will not know when is the right time to buy, and when is the right time to sell. So, technical analysis will help us determine when to buy, and when to sell coins.