The highest ability, fastest learners disproportionately leave the field over time. They have a multitude of other ways to profitably leverage their intellect and skills. Software development carries serious opportunity cost. Again, this is ironic because one would normally expect the best to stay and worst to leave, but that's not what we see in the data.
https://whoisnnamdi.com/never-enough-developers
https://whoisnnamdi.com/never-enough-developers
Who is Nnamdi?
Why We Will Never Have Enough Software Developers
Developers are dropping out of the profession in large numbers