Hindsight bias — the "I knew it all along" effect — is the tendency to perceive past events as having been more predictable than they actually were, once you know the outcome.

Why It's Dangerous

Hindsight bias distorts learning from experience. If you convince yourself you predicted the outcome, you don't examine the actual reasoning failures that preceded it.

Examples

• After a stock crashes: "I always thought that company was overvalued"
• After an election: "It was obvious who was going to win"
• After a failed project: "The warning signs were there from the start"

Consequences

• Poor post-mortem analysis — you don't identify what you actually got wrong
• Overconfidence in future predictions — you believe you're better at forecasting than you are
• Blaming others unfairly — "They should have known" is often untrue in the moment

Fix

Keep decision journals — written records of your reasoning before outcomes are known. This is the only way to hold your past self accountable honestly.

Reference:

Wikipedia: Hindsight Bias

https://en.wikipedia.org/wiki/Hindsight_bias