This is a fascinating thread. The overwhelming predominance of introverts in general and INTJs in particular is amazing. As an ENTJ, this thread raises a few questions for me.
First, is an introverted personality more likely to make someone *want* to retire early? Are introverts somehow more strongly motivated to get out of the workplace as soon as possible?
Secondly, is the focus on the introvert/extrovert split the most important factor? 68% of the respondents are NTs. Are the analytical skills and discipline of the NT personalities what makes the majority of the folks who responded here *capable* of ER? Could it be that almost everyone really wants to FIRE--the NTs are most likely to have the skills to pull it off.
Lastly, and most importantly to me as an extrovert who's 71 days from retiring, are introverts more likely to be happy in ER? Reading about the requirements of a successful retirement is a minor hobby for me. Fairly consistently I read that, in addition to FI, one must pay attention to health and fitness, intellectual stimulation, and have a healthy network of friends and family. Most of my friends over the years have come from my work. This is the one area I'm worried about in retirement. Are introverts happier in retirement because they don't *need* as many social interactions. I'm not suggesting that I's on a MBPT are hermits hiding from all social interaction. But I wonder if they have have a stronger immune system against feelings of social isolation?