My intent really is not to dump on anyone who finds Meyers-Briggs interesting, but for those who are interested in personality traits and want to learn what science has to say about them you may want to look at the Big 5 personality traits. M-B has long been discredited because of a complete lack of supporting evidence, but the Big 5 are actually supported and the subject of ongoing research. More here:
https://www.livescience.com/41313-personality-traits.html
https://en.wikipedia.org/wiki/Big_Five_personality_traits
Again - if you have fun thinking about M-B, have a blast. But if you are interested in it then you might also enjoy learning about the Big 5.
The Big 5 looks interesting, but I didn't see much data to show that it is any more predictive than M-B for job performance,
Frankly, I don't really care how good M-B is at predicting job performance. The reason my company used it was to help, the largely INxx group of engineers communicate with everybody else and vice versa. But the whole point of FIRE is not to be working. The Big 5 very well maybe better for this role.
Obviously, this survey suggests that all personality type can be part of FIRE movement. It would be interesting to see the difference folks who have actually done it vs those are aspiring to become FIRE. The fact that INTJ and INTP are ~5% of the population and yet 50% of the FIRE movement too huge a discrepancy to be mere chance. I am sure there is some ESFP who has retired earlier, I just have yet to meet the person. We have 3 people say they are ESFJ (.5%) vs 12% of the population again a massive difference. It is entirely possible that only M-B is good at predicting at being able to retire early..
As a practical matter, I think it is moderately important. If somebody who is a ESFJ, is expressing doubts that will be happy in early retirement, I'm not going to encourage them, an INTJ, expresses doubts I will share stories about how I as INTJ really enjoyed not working.
Poll