>[extrovert] children who grow up in more prosperous homes are less likely to face the kind of stressful events that undermine self-confidence.
Is extrovert synonymous with confident or that strongly correlated? Why should an introvert not be confident in themselves and their abilities?
>Extraversion [...] is the state of primarily obtaining gratification from outside oneself.
>Introversion is the state of being predominantly interested in one's own mental self