for me, it is many factors. I live in a very "safe" neighborhood... but simply read the newspaper and the next shooting you come across the police will be amazed that it took place in such a "safe" neighborhood.
A few months back, my aunt passed away from cancer. when driving to her funeral, my uncle's brother was shot and killed while reading his newspaper on a saturday morning in front of his porch. he was simply sitting outside reading the paper and drinking coffee when some gangbanger shot and killed him for no reason. his family and neighbors didnt notice he was dead until hours after the incident. he was survived by two sons, his wife, and his daughter.
this really made me realize that no matter how wealthy or how good of a neighborhood you live in, you must always be responsible for your own self defense. the things my uncles brother's family is having to go through right now is truly terrible, with all of the people in court and our flawed justice system, i would not wish it on anyone. we must do whatever is possible to prevent such a thing from occuring.