In a computer model of 1,000 fictional 40-year careers, the most highly talented individuals reached the top in only 3% of simulations. Extreme success usually went to moderately talented people who encountered an exceptional run of luck.

People riding an illuminated escalator at night

Success stories become cleaner in hindsight. The uncertain launch becomes a master plan. The chance introduction becomes evidence of superb networking. The employer who happened to say y...