Hindsight Bias

Believing after the fact that an outcome was obvious all along.

Hindsight bias quietly rewrites what you thought before the event, which makes it almost impossible to learn from a forecast you never recorded. Every bubble looks unmistakable afterwards and looked like a reasonable argument at the time. Keeping a written record of a decision and its reasoning is the standard defence.

Hindsight bias made the collapse feel predictable, though none of his notes from the time say so.