Me too.
When posting, I usually check in about an hour to see if anyone's replied. If not, then the worry factor is amplified and I start to think that no one liked it that's why they didn't reply to it, that they don't like me.... and so on.
It is mostly just the anxiety speaking.
If I think logically ,I know that's not the reason but when fear rules logic flies out the window and this is one arena where fear dominates.

That said often times when I read a post, I don't reply because
1. I don't know what to say,
2. It hits too close to home,
3. I can't relate at all, be it through lack of experience or otherwise.
Maybe its like that.