I suspect most people linger and never bother creating an account. My own account is 103 days old, but I've been RSS subscribing to HN for about... 3 years? Maybe slightly longer.

I read a lot of what's being discussed on HN, but I barely participate.

Partly this is down to me fully accepting most of you know more about nearly everything than I do, and sometimes people can be a little unforgiving in reminding others of that. Partly because a lot of the time, I find I can get the information I want from a discussion by just through what others have discussed.