A surprising kind of (a lot of) active users: Those who don't ask question.
Robert Israel 2,729 Answers, 0 Questions.
Brian M. Scott 5,847 Answers, 0 Questions.
André Nicolas 5,528 Answers, 0 Questions.
Arturo Magidin 3,329 Answers, 2 Questions.
I found it quite strange that there are high reputation users that are very active in math.SE (they probably spend much of their life in mathematics) but do not ask anything. It seems strange for two main reasons:
In mathematics it is very easy to find a problem that you cannot deal with, regardless of your academic level. There should be no problem asking because of the excellent quality of the site: People who frequently visit math.SE often know the high level that users have and the quality of their answers. Asking in math.SE may be the quickest and easiest way to find a solution to your question. Undoubtedly, when the "valued users" need help, an answer is a tiny way of paying for their work on the site.
Discussing and asking helps us to learn, we can always ask and learn more, and we very often want other people to opine on a topic in mathematics that interests us, to know other approaches.
I have two theories:
They are embarrassed to ask or want to maintain some type of image (in the latter case using other accounts to ask).
They always can help themselves or have external help.
I think I need an explanation to this so common phenomenon.
sci.math.research. If you were, you'd have known that Robert Israel has been answering questions since around the time you were born. :-p $\endgroup$