…while reinforcing their power over the victim by making the victim swallow unfairness. (And humiliating the victim, making the victim participate in their own humiliation, can bond the rest of the family together.)
Extracting value from a victim when they become adults still keeps the victim there at the bottom of the hierarchy…especially since those abusers are making demands as if they are above the victim, even though they no longer have outright power over them.
Even as an adult, the victim has low status in the family, and that status is reinforced through emotional abuse and bullying that activates the victim’s conditioning from childhood. They attempt to coerce or force the victim into acting as if they have no power, acting low status, and this maintains the existing hierarchy and power structure even as the victim technically has power as an adult.