Jehovah's Witnesses: why are demons really aggressive to some people...?

like ive heard stories of demons grabbing a guy by his throat and throwing him out the door, grabbing a guy by his hair and yanking him out of bed, or making people go blind, etc. but you never hear a story about one of jehovah's witnesses (not the ones that are just now converting, the ones already jws) being attacked. why is that?