Fundamentally, the history of a price has nothing to do with its future price. The laws of nature do not care if you are on a bull run. So TA is completely bunk in that regard.
However, obviously many people do rely on TA, which means TA is influencing the price (you can beat their TA algo with your own TA algo). The problem is, you never really know what everyone else is doing. Relying on TA amounts to playing rock-paper-scissors, blindly, with 1000 opponents, and hoping you choose the winning move against most of them.
Keep in mind there are only 2 outcomes, win or lose, and they occur randomly, so it’s really easy to fall victim to selection bias and think you have a winning TA-based algorithm.
However, obviously many people do rely on TA, which means TA is influencing the price (you can beat their TA algo with your own TA algo). The problem is, you never really know what everyone else is doing. Relying on TA amounts to playing rock-paper-scissors, blindly, with 1000 opponents, and hoping you choose the winning move against most of them.
Keep in mind there are only 2 outcomes, win or lose, and they occur randomly, so it’s really easy to fall victim to selection bias and think you have a winning TA-based algorithm.