Kilted2000 originally said, "I've noted that". This is something that also occurred to me when I first joined XMarks. Yes, most seem to be from America. Most older guys and therefore probably more vets. I would suspect that leaving aside the people who join out of curiosity for a short time, the bulk of members is not military/clergy. Most members are those that are looking into what is proper and best to get started killting, who may stay for the interesting questions/answers. Those who have been referred here for information are probably similar to those who are interested in their first kilt, to whom I suggest checking out this site.
Like any other group, there are the few who are more prominent and the many who actually make up the group that the few become a figurehead of. The prominence of posts by certain folks varies over time. For instance, there have been many mods who posted frequently in the past but now join in infrequently.