I'm glad Susan Cain's book came up. That book was a game changer for me because it was the first time I saw my introversion as a strength and not a weakness. Heavy drinking and drugs was what it took for me to "enjoy" socializing, partying and feeling at ease in groups.
I do have the benefit of a spouse to avoid isolation, but I am grateful for my introversion. It makes it easy to avoid alcohol. Also, embracing me for who I am has allowed me to focus on the largely solitary pursuits that have been a big help in rebuilding a sober life, i.e. reading, meditating, cooking, studying toward the next level of my professional designation, etc.
There are also ways to be introverted and still enjoy being around people and interacting with them.....art museums, classical music concerts, reading at a coffee shop, online forums, online book clubs, etc.
I recently had a great stay at a vacation resort that caters to people who want a quiet stay away from the hustle and bustle of a popular tourist area. Someone complained in an online review that they didn't have a pool bar, and their response was that they didn't have a pool bar because that type of traveller wasn't their target audience!