> That's why people go to grad school, participate in a hobby, or join a sub-culture to make their world smaller again and limit their choices to make themselves happier.

I don't think people do those things to limit their choices to make themselves happier.

I think they do those things because the act of being at grad school, or enjoying a hobby or sub-culture makes them happy.

In other words, people don't do those things to socialize with fewer people; they do those things because they enjoy doing them. Socializing with people who enjoy the same things they do is a pleasant side-effect.