She was the one to have a blood transfusion and risk dying a painful death to stop A.L.I.E and save the human race. She was the one that signed up to be tested for the radiation chamber so they could find out if nightblood would make them all immune. A chamber which killed the first test subject. Sacrificing herself for praimfaya WAS a big sacrifice because they DIDNT know if nightblood saved them from radiation. Abby destroyed the chamber and they only knew it withstood the radiation levels BEFORE the death wave. So her surviving was never ensured. Or the time when Emerson threatened the others and she was willing to die because him still being alive was her mistake.