Hero or Runner

Why is that that some people risk their lives for others and some people rather save themselves? I think some people choose to risk their lives to help others because they want to make up for all the wrong things they did wrong. Some people will say no it is only because they want the money, but actually most volunteer to save lives such as firefighters. Maybe they just want to be the hero at the end of the day but I know stories where people who had a horrible past and got in trouble decide to change their ways and to correct themselves they will volunteer to help. On the other hand, there are people who rather save themselves . I do not understand why they seem themselves as more important but they do. They would rather risk the lives of others to make us they can live one more day. In times of trouble though we find out what kind of people we are. A hero or a runner.