@Nebuchadnezzar_II You're arguing against things I didn't actually say. I never said drawing a trendline tells you how long a trend will last, or what will happen when it breaks. I was giving someone who explicitly said it was their "first price analysis" some basic guidance on how to make their chart less cluttered and identify the larger structure.
And yes, a line by itself doesn't predict the future. That's precisely why I was talking about identifying swing highs, swing lows, zones, and structure rather than pretending a line has some magical predictive power. No one can predict the future. that is obvious.
As for Rayner, you're free to dislike his marketing. I recommended his tutorials because I found the material useful for learning basic chart structure. That doesn't mean I'm endorsing every claim on his website or claiming he can "consistently beat the markets."
You also seem to have interpreted my "Just study first" comment as me claiming that I have some secret ability to beat the market. I didn't say that either.
If you want to argue that technical analysis has limited predictive power, that's a perfectly legitimate discussion, but that's different from telling me that I don't understand what I'm talking about based on a tutorial recommendation.
I'm still learning too. The difference is that I'm actually trying to understand the structure before drawing thirty lines on a chart and calling all of them support and resistance.