Whoah, no, I don't think that's silly at all. My windows are all ground floor facing the parking lot and I always keep the blinds closed. If I want more light I open them slightly facing up and make sure the curtains are completely closed.
Thinking about it, though, I'm probably not a very good example. I get paranoid somebody will look through the little crack between my blinds and the vertical sides of the window. I have to push the blinds into the frame to get rid of the gap.
I have also never been stalked or had a break-in or anything. I just hate the idea that somebody might look in my window. I don't want people to see me, I don't want them to see my stuff, I don't want them to see my son especially. Just, yeah, feels unsafe. My family thinks it's weird to keep them closed all the time while I can't fathom having them open like they do.