A lot of people choose to be mediocre developers, but likewise a lot of people try very hard to be good but simply don't have the cognitive capacity or organization to excel.
(Cognitive Ability) * (Engineering Ability) * (Problem Solving Ability) * (Attention to Correct Details) * (Eagerness to Labor and Work)
There are real 10x engineers. And there are also 0.1x engineers. And plenty in between.
And lots of things impact job performance. Burnout, life satisfaction, interesting problems, ...
A lot of people choose to be mediocre developers, but likewise a lot of people try very hard to be good but simply don't have the cognitive capacity or organization to excel.