I take it you are very young. To be that naive that you haven't gone through life and haven't been on the receiving end of someone that either wants your stuff (and may kill you for it) or just hates you because of who you are. Everyone has enemies, they either know it or not. There are cultures out there that will kill you on sight because you are their enemy. Whether you believe that or not is only relevant when you go outside your bubble and go to these places.
Consider the article below. This woman didn't believe she had any enemies and it cost her her life.
http://www.nytimes.com/2008/04/19/theater/19peac.html