There is more to life than simply looking out for "Number 1". At some point and time, reality is going to require you to look out for someone else in addition to looking out for yourself. There is nothing wrong with making your own safety and well being your top priority, But it is also true that anyone whose life is of any value in this world will find themself at one time or another doing something valuable for someone else without any expectation of reward. The easiest examples to cite of selfless service are those who place themselves in harms way for the good of others and sometimes loose their life for having done so. ie the members of our Military, Fire Departments and Police Departments.
If you are a husband, it is morally correct to protect your wife from harm. If you are a mother, it is morally correct for you to protect your children from harm. If you are an older brother or sister, it is morally correct to protect your younger siblings from harm. There have even been well documented cases where a young child has picked up a firearm or other weapon and successfully went to the aid of their mother who was being attacked. It is not only morally correct to help others in a crisis situation, it would be bizarre for someone to ignore someone else who is in dire need of assistance if help could be easily rendered by the first person.
There are many responsible citizens in the United States who own firearms and many of those gun owners are highly trained and or extremely competent with their firearms. In some localities, a private citizen is allowed by law (or not prevented by law from being able) to carry a concealed handgun in public. In other locations, a private citizen is perfectly within the law to carry a handgun in plain sight of everyone. How do you feel about that?
People generally feel safer in public places rather than in secluded places because they believe criminals are less likely to attack someone if there are a lot of witnesses who could testify in a court of law against said villain. Do you think the average person would feel even safer if they somehow magically knew that there were armed, undercover police officers walking among them in that public place? How do you think the average person would feel if they magically knew that there were even more highly trained, well armed private citizens who were mentally and physically prepared to selflessly defend an innocent stranger from violent attack if they happened to witness such an event? How safe do you think that person would feel if they magically knew they were surrounded by such an army of heroes?