When I’m not in a funk about what a horrible writer I am, I actually think this is a good thing. The instant a person starts thinking they have nothing to improve, that they’ve finished growing, they stop looking for ways to improve. They stop getting better. In fact, this is usually the time their work starts to go downhill.
…Of course, when I’m actually in the “Oh God I’m so horrible at this why does anyone read my work?” it’s pretty much impossible to keep that perspective.