>> it is solely by choice (and probably fear of the unknown)

Or because of the social benefits. You state that you consider your former self a freak, and consider your current self a completely asocial misanthrope. I was following a very similar path to you, but realized that I was on my way to being a social outcast. To me, being a C++ programmer was not my purpose in life (although it was a very interesting field I ended up making my career). A great deal of what I see as the "purpose of life" consists of those social relationships. If I didn't have those, C++ wouldn't make me happy, so what would be the point of it all?

I don't mean to sound argumentative - I'm just pointing out that although I was capable of doing more, I chose to stay close to my own age group because of a legitimate quality-of-life benefit. You did state that it's by choice, but I think that's an aspect a lot of people don't consider, especially the author in question.

It is only because high school is the default that those who choose other options feel isolated. Those >25 usually find friends without resorting to spending most of their day in the same overcrowded fishbowl. If 16 year-olds were spread out across various activities, they would make the effort to find each other, but it's easy to exclude those few kids who aren't seen at their lockers everyday when school is the norm.

In many locations, employment of minors (< 18 years old) is limited to family businesses.

Here (USA, Washington state) we have major limitations and it's hard to employ minors.

Signing contracts, however, isn't hard and so I worked as an independent contractor (1099) :)