They like the salt. It is not the best food to give them, according to my vet cats can not digest things that are not protein, plus all of the grease and calories aren't good for them. Mine will go for chips too though, one eats them and the other one licks the salt off if they get a hold of one. I really have to pay attention when we have chips that the kitties don't snag one.
My cat is named Piggy. He will eat literally anything. Dog food, chips, goldfish, even edemame. He also will wait at the door at night when we go out to smoke and if a bug comes in he will stalk it and eat it. Nothing quite like hearing your cat crunching on a beetle!
Honestly... Chips are unhealthy enough as it is (depending its type) it's only going to do the same amount of damage as it does to me or you... Cat, dog, or bear their animals and will eat anything if they really had to, it'll be fine