The self-serving bias is the tendency to attribute successes to internal factors (your skill, effort, talent) and failures to external factors (bad luck, other people, circumstances).

Classic Pattern

• Got the promotion: "I worked hard and earned it"
• Didn't get the promotion: "The process was unfair" / "My manager doesn't like me"

Why It Exists

The bias serves a psychological function: it protects self-esteem and maintains motivation. A complete absence of self-serving bias is actually associated with depression.

Where It Becomes Destructive

• Prevents honest self-assessment and skill improvement
• Creates interpersonal friction — if your failures are always someone else's fault, you'll never take corrective action
• Distorts team dynamics — individuals take credit and distribute blame unevenly

Calibration

After a failure, ask: What is the one thing I could have done differently that would have changed the outcome? Anchor on your own agency, even partially.

Reference:

Wikipedia: Self-Serving Bias

https://en.wikipedia.org/wiki/Self-serving_bias