They abuse because they like doing it and because it works, it gives them power
Prov. 13:19a A desire fulfilled is sweet to the soul,
John 11:48 If we let him go on like this, everyone will believe in him, and the Romans will come and take away both our place and our nation.”
Shows that power-over is the real motivation for abusers. False logic.
Also 12:11, 19
John 11:50 Nor do you understand that it is better for you that one man should die for the people, not that the whole nation should perish.”
They abuse when it is in their best interests to do so.
The generational transmission of abuse
To some degree, abuse can be a learned behaviour.
Gen. 4:23-24 Lamech said to his wives: “Adah and Zillah, hear my voice; you wives of Lamech, listen to what I say: I have killed a man for wounding me, a young man for striking me. If Cain’s revenge is sevenfold, then Lamech’s is seventy-sevenfold.”
Lamech was five generations down the line from Cain. Cain called the city he built after his son Enoch (v. 17); this hints that Cain took care to raise his son Enoch in his own likeness. After five generations the wickedness Cain had modelled to his offspring had been reproduced and entrenched to the point that Lamech was a boastful and bold abuser, who felt he could take human life at will. Imagine how his wives would have felt with such a murderous and lawless husband!
2 Sam. 13-19 – The generational passing down of sin in the story of David and his sons, Amnon and Absalom.
A Cry For Justice 