Eating expired potato chips will not make you sick but after the potato chips expire they become stale and not as tasty or crunchy.
I've eaten expired potato chips for many years now and never once have gotten sick because of it.
It's best to eat the potato chips before they expire to have the best freshness and best taste but just because potato chips expire it doesn't mean that they are bad to eat.
A lot of potato chips go to the trash from stores that are not sold because they expire and I will sometimes when I see them get them out of the trash and then eat them later.
They are not the greatest tasting chips but they are very safe to eat.