This is still something I really can't wrap my mind around. What is the key difference in early life between people who will speak authoritatively regardless of competence, across the spectrum to experts who can't or won't? I don't think Dunning-Kruger explains it because it's not like every shy expert used to be a gregarious beginner.
I have seen lots of talks by experts about the technology they're experts in, but I have seen lots of the other kind as well.
I think Dunning-Kruger is part of it, but also excitement.
If you are the expert you probably got that way by putting in a lot of time, you are at any rate older than when you started out and you may be in fact be quite older than the average developer, often older people do not have the same enthusiasm and excitement for things (although sure there are many that do) so that cuts down the number of people who have experience who also have enthusiasm for getting up and talking.
Getting up and Talking means doing work for it, if you have kids you may not want to do that work unless your job is one where you have to do it. So if you are an older expert with kids but not employed in an evangelist role you probably are not going to go out and do talks.
The expert in a subject may see so deeply into the subject that it is difficult for them to express the gee-whiz aspects that will attract other people. Those who know more are not necessarily able to express that knowledge in an interesting way.
The expert may have lost interest in the matter as they gain in expertise, or they may think things that others will find amazing and interesting to be so obvious and trivial as to not be worth expressing.
For these reasons it may be that talks on a subject are preponderantly given by those with less than expert mastery of the subject.
I think there is some personality difference, but also one of values.
Do you think or feel it is shameful for you to give introductory talk? Did you grew up in environment where such thing was mocked or did you grew up somewhere it was praised? Do you think it matters super much if someone in audiemce looks down on you or are you rather motivated by single person that likes you?
Do you think you need to be super awesome experienced speaker to make first public talk? Are you ok having public talk with primary purpose being to learn doing public talks?
These imo make the difference. It is not like there would be lines of experts wanting to talk.
