The vast majority of users never post an answer or a question, and most of those that post only once or twice never get upvoted (or get downvoted more than upvoted), so their reputation stays at 1.
I think they said a couple years ago that over 50 or 60% of registered users have 1 reputation.
I think they said a couple years ago that over 50 or 60% of registered users have 1 reputation.