Ayin Hara (or “Evil Eye”)

I have found that the words “Bli Ayin Hara”, (without an evil eye) are very common in Israel. As time went on I found that some people turn the idea of Ayin Hara into something that controls every facet of their lives. Some people don’t have guests over because they don’t want people “looking” at all the stuff in their house, so the guests shouldn’t look at their belongings with an “evil eye” and cause a loss. I don’t know if I’m required to believe in this “Ayin Hara” business or if I can just assume that everyone is good and looking at me and my family in a good light. If you could please shed some light for us on this subject we would be so grateful.