Vengeance sizes a soul quickly and settles in the heart like poison. Khan knows the business of vengeance better than anyone - from the moment they revived him from sleep, he knew his purpose.
What would you sacrifice for family?
Everything.
Except he is superior. Self-sacrifice never enters his mind, because depriving the universe of his supremacy is a sin... if such intangibilities exist.
So instead he destroys everyone less than himself. Brutally uses others to ensure his successes. Offers a little in exchange for it all.
Sacrifice everything for family.
No one said it had to be his everything.