As we now know too, if Zodiark dissipated, all their souls would return to the Lifestream. So it seems the Ancients who were okay with the 3rd sacrifice just could not accept the fact that the End of Days even happened to begin with, they rejected reality. Because if they knew the souls would return to the Lifestream upon Zodiark dissipating, why bother doing the 3rd sacrifice to begin with, the souls were just going to be reborn anyway.