As I grew up, I realized how stupid and immature it is to try to blend with the rest of the crowd, where extroverts naturally stick out and introverts feel like they are doing something wrong and should emulate more visible ones. Embrace yourself as you are, focus on aspects you don't like yourself but enjoy the rest, it can be a real strength if you use it well.
Friends and family are one aspect of it, but also how you approach hobbies, traveling etc. Ie my extroverty boss can't simply go to gym, he has to go with some friend. So he goes rarely and he sucks in it. Bunch of friends simply can't travel alone, while I repeatedly explained to them that ie backpacking around the world alone is extremely positive and character-building experience that can't be achieved in any other way. So eventually one of them went, but for 2 weeks only to effin' Singapore and not a step further, to hang out with former colleague for 2 weeks. While having amazing places to keep discovering all around him, or ie jumping on a plane to Bali/Lombok/Gili islands for a week.
I would venture to suggest even that your boss can't simply go to the gym because he doesn't actually want to go to the gym. He wants to socialise inside a gym.
I don’t know you, but I have a feeling that you’ll eventually come to understand “extroverts” better than this.
Introverts have an inner model of the world. Extroverts rely directly on the world.
It doesn’t mean that extroverts like people more or that introverts necessarily prefer being alone. It’s just that for extroverts, when nothing external is happening it’s like a little death. And for introverts, we need down time to reconcile our inner model with all of the day’s external stimulation.
This definition of introvert seems closer to the term "need for cognition".
My wife and I are polar opposites in that regard. She can never seem to have enough friends, and they talk often. I think one big difference is how people are with nothingness. Because no matter how busy our day is, there's always periods of downtime...on a bus, on a walk, before bed, etc.
For example, I could sit in a chair and stare at nothing for a long time and not get bored. Mind always wondering, planning, thinking. She on the other hand gets bored and stir crazy in short order. And having people to reach out to chat with is a good cure for that.
I'm not suggesting one is better than the other, of course, just another difference in people.
All of that is to say, people like us who at least -say- we don't want more friends make it harder for people seeking, by removing ourselves from the pool so to speak. And I'd imagine between marriages, kids, work, etc... there's a lot of us like that.