What about all the 2 mile specialists that are busts. For example here are the top 3 2 milers of all time
Lukas Verzbicas -> did nothing in college
German Fernandez -> Had 1 good year and then did nothing
Jeff Nelson -> pretty much nothing
The 1500m list is like 50/50 (i.e. for every Jim ryun their is a Tim Danielson).
The top 10 800m list is
1:46.45 Michael Granville (Bell Gardens, California) 1996
1:46.58 George Kersh (Pearl, Mississippi) 1987
1:47.31 Pete Richardson (Berkeley, California) 1981
1:47.55 Donavan Brazier (Kenowa Hills, Grand Rapids, Michigan) 2015
1:47.59 Cameron Cooper (Oak Park Michigan) 2017
1:47.67 Carlton Orange (University, Memphis, Tennessee) 2015
1:47.67i Josh Hoey (Shanahan, Downingtown, Pennsylvania) 2018
1:47.68 *Elijah Greer (Lake Oswego, Oregon) 2008
1:47.74 Alan Webb (South Lakes, Reston, Virginia)
1:47.79 Andrés Arroyo’ (Colonial, Orlando, Florida)
Kersh did OK for himself. Brazier has done fine. Webb has done fine. A couple are sort still early on (Hoey, cooper and orange). And a yes a few are busts.
You would really need to look a bit deeper (say top 50) to figure out what the trends are but in pretty much every event there is a lot of burnout or people that just never take that next step.