Hmmmm.... not sure if I can tell who posts the 100,000 post!!! Don't think it tells me that one.... The post above has post number.... 102,961, as all the posts that get deleted, those post numbers are not used again by the system / those posts sit idle where we can restore them if we need to. So the post count is technically over the 100,000 mark, however; its not by legitimate posts that are actually present upon the forum for viewing.
I guess when we get closer to the figure, we could mark a posts post number, then look at how many posts are remaining and that post number would be the 100,000th poster.... though again, it couldn't be done until getting close as deleted posts would affect the count between the frontend of the system and the backend database numbering (what we see vs. computer stuff).
Soooo.... maybe we can find the 100,000 poster afterall!!!