A.C.C.-Is It Always OK to "Look Out for #1?"

I believe that "looking out for number one" is a rule that depends on certain situations. For example, would you rather sharpen your pencil before or after someone behind you in line even though you've been waiting longer? But if there was someone more important for the safety of the people about to be tossed into boiling lava, would you save yourself or sacrifice yourself for the good of the people? So I believe that you are given choices for you to decide. If you do whatever someone asks you to do no matter the circumstances, people will see you as an easy target to do their dirty work. If you don't do anything to help other people at any time in your life, people will see you as an inconsiderate jerk that helps nobody but himself (A.K.A a Scrooge). So I believe that you should vary these "looking out for number one" situations.