do i lay KK down when i am 95% sure i'm up against AA? no

Wow. Why do you hate maths? Just look at this sentence. If you are sure you are 95% against AA THEN YOU LAY DOWN KK. You are something like 17% to win in this precise situation.

As Pelion argues eruditely, there are compelling reasons to lay down a set in this hand. But fighting the mathematics isn't one of them. It will always win.