Why are american people so afraid of the Internet (facebook)?

After reading the articles, the posts and having been in the US for about three weeks, I'm beginning to see this paternt in what students and teachers say about the Internet and especially Facebook. Lots of you are afraid of what Facebook can do to your life and your future. I don't know if is just because I have only knew Facebook for some months, but I don't really see all the problems that a lot of you see. Yes you can get addicted to it, yes your employer can find out about things about you and yes if you write in your status that your are away from your house the next days, weeks, months somebody could rob your house, but seriously about the addiction; no matter what you do in life if you do it to much it's not a good thing. And if you just think a bit about what you post on your profile, than it shouldn't be that much of a problem if an employer finds you.. I would really like to hear from you, what you are so afraid of since I don't really understand it.