Amerian culture highly favors people with great social skills. It's hard on introverts to go to job interviews and not look disinterested or "standoffish." My mother told me that I was "standoffish." Both of my biological parents had excellent social skills, They were ignorant as a box of rocks, unmotivated to achieve anything, and violent - but people loved them because they had the "gift of gab" and seemed so down home and folksy. As for my "career" success, I learned that working for temp agencies would get me hired much faster than an interview because they could see that I was capable even though I was quiet and withdrawn.
In the '70's, I recall a Watchtower article that recommended not being an introvert (and, to some degree, it might be a choice?) but, rather, a "happy, loving extrovert." I maintain that extroverts are neither more happy nor more loving than introverts, though I can understand how it might appear to be the case.
As I've gotten older, I've come out of my shell a lot. After having to look for jobs for much of my life, endure countless interviews, and interact with crazy religious people and wacky co-workers, I've learned to appear more friendly and talkative.
I, and most introverts, I would wager, like myself just as I am and cannot see the possibilty of any growth or gain by not being just the way I was made.