Setting aside the possibility that the O2 is just to calm people down in a bad situation that they can't do much about... The thing they tell you on a plane about putting your O2 mask on first so that you can help others, is actually how all of life works.

In general, you cannot sacrifice yourself to do good for others, you have to take care of yourself & live a good life in order to be able to help others.

You can't sacrifice your relationship to prioritize caring for the kids, you have to work & maintain your relationship to properly care for kids.

You can't sacrifice your income or your health in a "pandemic" to protect the sick & vulnerable. How can you help anyone if you can't even help yourself?

People preach sacrifice as a means to destroy & enslave others.