The biggest problem with people is that they tend to make the same mistakes. You realize there is a problem, but when it occurs, you still continue to make errors.

Great people are those who constantly review, reflect, and analyze, reducing the chances of repeating past mistakes, but it's very difficult to eliminate them entirely.
The same applies to trading—people find it hard to align their knowledge and actions, often habitually making the same mistakes. Then they go through a cycle.