Why does the religious father, whom people praise for his extreme harshness, constant shouting, and excessive greed for money—especially with his young son and family—always see himself as in the right?

The father is advised to embody good morals and to be gentle with his children. Firmness is not harshness, and Allah grants for gentleness what He does not grant for violence. Children can advise him respectfully, or through a relative or a righteous person. It is the children's duty to honor their father and treat him kindly, no matter his condition, for honoring him is among the causes of Allah's pleasure.