See I take issue with this: this is the prevailing narrative but I just don't buy this story. I think it's a grotesque oversimplification and a mislabelling of what's happening.
Confident people (not necessarily extroverts) have an evolutionary advantage. In the days of hunter gathering and in early human history these were the people who became leaders and told people what to do and over time those traits have tended to be plentiful in people who lead. These are people with authority, but not all of them are extroverts. It's true that extroverts sometimes have a superficial advantage in social situations because this is their natural environment but they are not necessarily leaders or in control. Often they are social butterflies and quite a lot of them are massive people pleasers. They frequently are the people who you notice first in a group but by no means always the ones with the most authority. (A lot of really extrovert people I know are alcoholics, btw).
Introverts (as others have pointed out) can sometimes be shy and uncomfortable but more often they are people with inner confidence who just need time out from social situations to be themselves.
For complex social reasons in recent years (and I'll leave COVID but that was a huge trigger) a disparate group of people who don't feel they fit in have rebranded themselves as "introverts" (largely inaccurately), because they think it makes them sound more interesting/deep. I presume because it makes them feel they now have a "tribe". It's become cool.
And like all tribes, you have to define yourself by finding an "other" (in this case "extroverts" (who usually aren't extroverts either) so they spend a lot of time talking about how they've all been sold down the river by dreaded "extroverts" because society has ganged up on them. I've read thread after thread with people calling themselves "introverts" and by and large they are not: they are people who are shy/anxious/pissed off/grumpy who think being an "introvert" sounds more interesting.
I think most of this is just people with a chip on their shoulder, grasping at straws. Of course the world is easier for the confident: this is hardly news. But the binary distinction between "introverts" and "extroverts" as if there were some conspiracy against quiet and contemplative people seems really paranoid. And it worries me a bit because I hear people on here and IRL talking about their "introversion" in the language of the radicalised. It's fine to be quiet or withdrawn but talking about yourself as if you are some oppressed ethnic group is a bit nuts.
And btw I'm kind of an ambivert. I have both introvert and extrovert tendencies.