I know why I ask questions -- to learn and to get help with problems I'm struggling with. And I have been incredibly impressed with the knowledge, eloquence, and responsiveness of the Stack Exchange community. When I post a question, it almost always gets some response within 10 minutes. It's like having a bunch of statisticians and mathematicians hanging out at a water cooler that I can walk around the corner to when I get stuck.
I am not surprised that some of my questions get answered. But I am (wonderfully) surprised that they almost ALL get answered, and almost immediately. What motivates enough people to spend enough time on this site, that there is almost always someone with specialized statistics training willing to write up and answer the question of a stranger -- often having to parse through the ill-formed/vague questions of beginners who may not know enough to know how to word a question clearly. Even if you're an expert in the subject matter, it still takes time to write out your thoughts and come up with examples.
One explanation is real-world reputation, but so many people use aliases that I don't think that can explain much. I imagine some people get paid to answer, but I doubt that can be much of it. There probably an intrinsic joy to teaching for some, but many of you are teachers by profession anyway. Is it truly altruism? (in the informal sense of the word) Is it about building and being part of a community?
I am very appreciative of this site and the people who answer questions. I'm curious to hear your thoughts.