I'm pretty much a loner, and tend to push away people who try to get close... sometimes i wonder how different would be my life if i wasn't like that. Only sometimes.
Being a socialite is always overrated if you aren't one by nature. If you really want to know how it feels, enter a committed relationship with someone who is, that way you can reap all the benefits of being a people person while not actually ever having to invest in being one.
I regret pretty much all of my teen years, say ages 13-20. My dad died when I was 12 and I had asperger's at a time and place where the teachers who were supposed to be helping me just thought I was just an ******* (of course they were half-right tbh) so by virtue of being depressed and anti-social I was a prime target for being picked on from secondary school onward.
That's all just background noise though, what I regret is how I handled it. Rather than work past my natural limitations and learn to cope with what I now regard as a very minor disability at worst I just stewed in it and when the teachers dismissed my grief and my anti-social behaviors as me just being a problem kid rather than prove them wrong like a better man should I fully embraced their narrative about me. I learned retaliation is the simplest action if you want people to just leave you alone and while I never really bullied anyone else I would go to blows at the slightest of provocations so that by high school everyone knew not to mess with me, for any reason, and I spent what should have been the time of my life depressed, isolated and "pretending to prefer being alone, thus leading to further loneliness in a vicious circle of solitude that young men of a certain temperament build for themselves and then inhabit."
I eventually came out of it with the help of two very special individuals who invaded my solitude and wouldn't leave it alone and am now mostly happy, though picky when it comes to friendships. Still I look back on my own childhood and all I can think is how much time I wasted in pointless misery and foolish self-pity, time that would have been so much better served...being a child you know?