The only data a trader can base his decisions upon are price, time and volume. Yet many traders don't use the latter, they don't use it at all or they only use the traditional volume bars. A trader should be aware those bars are only based on volume at a certain time, not volume at a certain price. This means the majority of traders use only price and time to trade, this gives you a disadvantage. And then there is also an infinite amount of traders who use their beloved indicators, indicators like rsi, macd, bands and many others. All these indicators calculate their levels by time and historical price, how are you going to foresee the future if you base your decision on history. To me a lot of indicators are totally pointless, they add no value to your trading. The only purpose is to make you feel in control.
A trader should only use Price action and Volume to predict future price.