As an introvert social interaction drains my mental energy so at some point you start investing more energy into enjoying your best friends than into making new friends.
2. There is this recruiting problem where you have to decide which secretary to hire before having seen all of them. The optimal solution is to see the first 37% (1/e) and then hire the first that is better than the previously seen best.
Putting that into lifespan of ~75 ys and assuming we don't really start sampling until we are 15, we end up with an optimal stopping (= exploitation) age of 32.07.
Surprisingly close to the 30 mentioned.
I figured, that for me, 37% (1/e) worked out to 13 people.
This (finding people) is a space I've spent a lot of time doing, planning, understanding, and thinking about :)
Also, there are a lot of scientific papers on how to model these in scholar.google.com (sorry that I don't have links that I can give right now)
I'm not an expert on psychological motivations, so I can't speak to the feelings or motivations of others, just myself.
Most of the time these results are things I find during introspection after social events are over. I can spend 4 hours in a social situation and be one of the drivers that keeps things going. It's later, when I'm alone and meditating, that I discover just how exhausted I was.
My wife is an introvert and is highly skilled at chit chat. She can work a room better than anyone but the most gregarious salesman types. She will remember the names of people that she met 10 years ago, details about their careers, their children's names and what their children studied in college. Doesn't matter if it's a professional event, a wedding, or a funeral, she is always on her game. BUT, she always goes home exhausted.
Have you ever wondered if deep inside you are an introvert that just got very good at pretending to be an extrovert at early age due to social pressure? Western society rewards extroverts.
Are you sure about that? I get the impression that the English culture regards extroverts as freaks of nature and terrifying monsters.