Hindsight bias is a psychological phenomenon where individuals perceive past events as having been more predictable than they actually were. In cybersecurity, this bias can lead professionals to unfairly judge decisions made before a breach, believing the risks or attack vectors should have been obvious. This can result in misplaced blame or overconfidence in future threat predictions. Recognizing hindsight bias is crucial for objective post-incident analysis and for fostering a learning culture that improves, rather than penalizes, security practices.