Why do crunchy foods like chips get chewey when go stale, and things that are supposed to be chewy like bread get crunchy?

Chips begin to absorb the moisture and the humidity of the air. This is why they are vacuum packaged with nitrogen as a preservative, sealed, or wrapped tightly. This is also why the worst feeling ever is when you have a BBQ in the middle of the summer and put out a bowl chips. 25 minuets later they become super soggy. Many products that can go "stale" have instructions to be stored in a "dark, dry place" such as a pantry. However, It is true that in drier climates this process is slowed.

Bread is made from water, flour etc., as opposed to chips which are made from potatoes and oil. Bread gets hard because it absorbs moisture which causes the starch compounds to crystalize, thus making it hard/stale.