Why are people not concerned about security on Internet Social tools?

Why are people not concerned about exposing their lives on the Internet? In a way that can put not only themselves but their family and friends in danger. Some info collected just looking ramdomly for profiles on some social network websites. Phones, credit card numbers, full address, if they have children, how many are they and their names, where do they study, where do they work, etc. You can find everything about everyone. They’re really not concerned, if someone they don’t know is looking at their profile searching for ammunition. We all read stories about people that met online “friends” and many stories that end very bad. So, why does this happen? It’s because our society lives to deify celebrities and everybody is triyng desperately to get a space on the moon and they expect that somehow they’ll win or become famous or escape reality, using these tools? Or is it just because they are naive and are not aware of the risks? What can we do about it?May be include a basic security concepts as a mandatory school subject. I would like to hear more initiatives related to prevent people from making internet one man’s/woman’s wonderland!