In the past several years, I've been in different environments:

—Living in a boardinghouse in DC with people who I didn't really know. This was alright for happiness, but horrible for productivity because I had no social motivation to get anything done, and it turns out humans are social animals.

—Living with my parents in Boston. This was better for productivity, since they were interested in what I was doing with my time and my progress towards my goals, but reporting my progress wasn't exactly fun and it caused tension in the relationship.

—Living in the Boston rationalist house with half a dozen friends. This had the same benefits of talking about goals and getting social points for making progress. The dynamic felt a lot better because I was interacting with peers instead of parents, and it was easier to vanish into my room for a couple days when I wanted to. Also having house coworking or strategizing events is a big plus. A majority of residents (possibly all) had a similarly positive experience.

—Living and working with Leverage Research in Oakland. Like the above, but more.

To answer your demographic questions, I'm 25 years old, originally from Boston, and think the introvert/extrovert model is extremely silly but will answer "mostly introvert" in the spirit of not screwing up your data.

I've slowly come to have a strong belief that the main problem with people I know who are suffering, or failing to achieve their goals, is living with fewer tribal affiliates than they "need".

This seems plausible.