Hi jpcmc-long time and all that! Good to see you again.
Your question is quite timely with so many of us concerned with monetary gain, Google placement, and fluctuation in our statuses on this site-among other things.
I've been thinking about your question most of the day and I honestly think everyone should do this as well-then we can identify what is valuable to us as writers.
Success is many things to many people, and for me it's not measured in dollars; I've been on the site for over 4 years and have yet to pull in $100. Certainly I hoped for financial gain, but it was simply not meant to be. So far!
What I have found most important here is being able to express myself honestly, to practice and improve my writing style, and to interact with and learn from other hubbers. Taking into account those variables, I am a huge success.