Stuttering is actually fairly common in children, but through gaining more experience in talking or working with a SLP they tend to out grow it. I believe it continues into adulthood for some based on 2 factors. First is the psychological aspect as you’ve explained but also never figuring out how to correctly articulate. Ive done a lot of work on the former (adjusting my rate, pronunciations, etc), so Im very fluent with the people im comfortable with. However I still need to work on the psychological aspect. My difficulties through Middle school and high school have led me to form social anxiety which is something Im still working on. Thanks for the post!