Based on Chapter 4 of the Sai Satcharitra, what are the primary reasons a saint takes an incarnation on Earth?

Chapter 4 of the Sai Satcharitra explains that saints incarnate when there is a significant decay of religion and societal order. This happens when people lose their way, focusing only on worldly happiness derived from wealth, status, and family, and turn away from the ultimate spiritual goal. As detailed in this chapter, saints descend to protect the humble and the weak, destroy irreligion, and reawaken faith among the people. They are described as being naturally liberated souls who undertake this difficult task purely for the sake of others, with no self-interest, to help humanity find the path to self-upliftment.