I was going back at some old 800m high school performance lists, and found a very talented athlete I was surprised did not run after high school.
His name was Xavier Moss. He ran a 1:49.99 at the Texas State meet to finish 2nd to Hector Hernandez (who went on to have a good collegiate career), but disappeared off the grid and it seems only stuck with football. I don't even think Xavier was ever fully dedicated to track back in high school (although he certainly trained hard in season, of course).
What are some of the best runners you can think of gave up running (maybe for another sport?).