What does it mean that the cost of miscategorization?

Putting something in the wrong category means the wrong actions get applied to it.

Example: A hospital classifies a patient's chest pain as acid reflux instead of a cardiac event. The patient gets antacids instead of an angiogram. The treatment protocol was executed perfectly — but against the wrong category. The error wasn't in the treatment. It was in the sorting. Every downstream action inherited the original misclassification.

Try this: Pick a decision you made in the past six months that went wrong. Trace the failure backward: what category did you assign the situation to, and what actions did that category trigger? Now identify what category it actually belonged to and what actions that would have triggered instead. Write both down side by side. The gap between the two is the cost of your miscategorization.