The people teaching you are drawn almost entirely from those who did well. The ones who followed the same rules and blew up do not write courses, do not post results, and quietly leave. So the visible evidence for any method is systematically filtered.
This makes advice sound far more reliable than it is. If ten thousand people each risk a large share of their account on aggressive strategies, a few hundred will have spectacular records by chance alone, and they will sincerely believe their process caused it. You are hearing from the survivors of a lottery, not from a controlled test.
When you assess advice, look for the denominator: how many people used this, and what happened to all of them. A strategy is only as good as its average outcome, not its best one. See also the broader entry on survivorship-bias.
Related: survivorship-bias, base-rate-neglect