Amazing that even TOS Khan has fooled so many fans. Khan was definitely a savage, he is ultimately governed by his rage. How is he defeated over and over when for all reason he should not? Because he can't control that superior temper, this is why he makes mistakes, Kirk goads him and he blindly falls for it.
Everything out of his mouth is masterfully crafted to get you to do whatever he wants. Sure that is how he would prefer it, but all the good guys eventually figure out that he is selling them a load of BS.
Every time Khan says he loves his 'family' or that he would spare your crew, or treat you well, he is simply playing you, and when you figure that out and the superior mind is fooled he losses it.