I give myself as an example. I'm 30 now, and up until my mid-twenties I could easily be considered introverted. I always got a strong 'I' on Myers-Briggs type tests. Other people told me I was introverted all the time as well,
I agreed. I loved my alone time, wasn't super motivated to socialize with others, and got drained by being with people.
I also happened to have weak social skills, and wasn't happy with that. As I improved my social skills, and gained the ability to better enjoy other people's company, I noticed a lot of my so-called inborn, introverted personality traits were lessening as the years went by:
-I wasn't getting drained by socializing any more, because it was easier, more fun, and didn't use up as much mental effort.
-I still appreciated my alone time, like everyone really, but I didn't crave it as intensely.
-My internal motivation to socialize and be around other people went way up.
-In time I started to want to hang around bigger groups of people and do louder, crazier things when I went out. It was almost like I got used to smaller events, and sometimes needed something more stimulating to get my social 'fix'
-I just got more chatty and outgoing in general.
Looking back, I feel a lot of my introverted tendencies were a result of a social skill/comfort deficit I had. They felt like a core part of my personality at the time, but looking back I don't know if they were.
That said, I still love spending some days all by myself doing nothing. But it's good to have the ability to switch into a social mode when I want to.