In response to fpb
The Most Important Reason: Because the Authorities Are Too Incompetent To Protect You.
Example: Being killed while calling them.
And for those who prefer the moral take: neither from the victim's side
nor from the standpoint of society
is it preferable to have a good citizen killed by someone who does not respect social values. The criminal has placed a lower value on the lives of others than is consistent with human dignity: society simply accepts his valuation when it is a choice of preserving a citizen and losing him.