Kitten No. 1 shows it: you can fit in boxes, no matter how small the boxes. You can hide in it, it is cozy, warm, dark, and you are jealous of your siblings for your great place.
Cardboard boxes can be broken to your heart's content, which the second little video hero does not want because he feels way too comfortable in it. As a former cave dweller, our velvet paws also feel safe in it, even if the senior hangover is a bit stressful from outside.
So if you want to do your cat a favor, let her have fun and allow her to play with the shoe, egg or parcel box to her heart's content before he ends up in the waste paper.