Yes, the point is that in your area of expertise you are likely to be more humble relative to your actual ability (but not too far off, on average).

However outside of your specific area(s) of expertise your confidence in your ability is likely to far exceed your actual ability (on average).

So experts are still susceptible to DK effect for areas that lie outside their expertise. Even (or perhaps especially) if they think their expertise gives them special insight into another field.