My brother. Average, bright kid. Played lacrosse in HS, not too much else for ECs. He did win a scholar-athlete award, but just at the school level. He was in a play, but just a small part. Got a BS from JHU (back when it wasn’t nearly as tough to get into) and then an MS in fisheries biology at Humboldt State. Worked for an Indian tribe in northern CA for a while, then for the Oregon Department of Fish and Wildlife for most of his career. Did lots of research on shrimp, trying to reduce the “bi-catch” (stuff you’re not fishing for but get anyway) in shrimping, to protect endangered and protected species.
About a year before his planned retirement, he and his research partner actually (after much trial-and-error) discovered a method of using certain kinds of lights on the nets that reduced the bi-catch by about 95% or so (apparently let the unwanted fish find the exits that they could get out of, but the shrimp couldn’t). Truly amazing results. They published, and the fishermen started buying the lights so rapidly that the sellers wondered what the heck was going on! In about a year they totally changed the way things were done in the industry, and maybe even saved a species or two.
He just kept at it. To most folks it would probably have looked as though he had kind of a plodding, government bureaucracy kind of job for 35 years or so, but he was slowly advancing things that mostly mattered to a small group of people. Then one day, a true “eureka” discovery!