It is interesting to hear that you had left for a while. That you didn't believe in the process. People like you and the magic of their friendships are why I stayed. Thank heavens your Finnish ass decided to stay!
Luckily nowadays I'm coming back every time. But about leaving in general, it happens to quite many people. They join, they start, they get disappointed when their expectations aren't met or they're not enjoying their stay in here.
Quite many just leave. I'm not sure how many come back after the original disappointment.
But we could tell ourselves that all the best ones come back? :P As we all can see where I and we all have got so far!