Just like some people are more intelligent than others, or more athletic than others... some are more self-motivated and can work through their own initiative rather than relying on external input (such as managers).
That's not a bad thing, either! We should encourage those self-motivated people to work however makes them the most productive members of our economy. That is incredibly crucial for the times that we live in.
I don't think it's that easy as self-motivation as a scale, it's all about the environment and task that makes people the most productive.
I always want there to be someone with insane amounts of grit and ask how they do it. Insane amounts of grit would be: - Six pack and can run a marathon when old. - Recognised in their field. - Earned enough through work (not through the insane rise in housing prices) to be able to stay in their home for a decade without working.
Checking all these boxes, would be the master of grit.