Although this post is preserved for historical reasons, today it is considered off-topic everywhere in the SE network, because it is a "Getting to Know You" poll question. Enjoy this post, but do not cite it as proof that you can ask similar questions.
More info here: http://stackoverflow.com/faq
Please note I am NOT looking for answers like
well I guess depending on the context that could be an acceptable answer.. But you know what I mean.
I am looking for answers like
"I cannot keep up with an ever changing field"
"That my data gets hacked"
Actual fears that developers have to deal with.