I haven't read many replies to this thread, but here are my observations based on a couple get togethers in the past year.
Our FIREscape event held in Ontario Canada this past year drew from the forums, Facebook, and other online communities. At that event we had about 30% of the attendees returning from previous FIREscape events (Camp Mustache Toronto). The majority were from Toronto/Ottawa/US Northeast. The attendees were a broad spread of ages right from "still in College/newlywed" to comfortably "retired seniors." Similarly, net worths around the room ranged from Many millions to many thousands. A lot of the folks attending had just only discovered MMM and the FIRE movement. This event is a three day weekend that can be attended without missing work, and I believe draws both folks aspiring to FIRE as well as those who have achieved the goal.
Conversely, at the Moab meetup, most of the folks were older with the youngest attendees being (a guess) in their late 30's. Everyone there seemed to be on one financial forum or another, and had a comfortable net worth. Many were retirees simply because you had to be in order to get a week away from the office to enjoy the event. Folks can attend this as a weekend event without missing work, but it is a big commitment in terms of travel logistics, planning and gear. It makes more sense to do for folks who either have vacation time available, or aren't working.
Both events were amazing and offered chances to network with others, make life-changing decisions, and come out the other side a better person, but to the poi8nt of this thread, they both show that the demographic interested in FIRE is very broad-based and includes a large group of new and old, and that fresh takes on the idea are still coming to us.