Do you remember playing with big cardboard boxes when you were children? I have four other siblings, and I recall a time when we taped two boxes together, cut out windows and doors, then played with it until it fell apart. Now when I see my own children doing it, I get it. It’s fun, and they feel like it is their own personal space. Especially the younger one, he drags it up and down the stairs, put all his toys in it, hides in it, and wants to sleep in it with his pillows and blanket. He was upset when his Dad wanted to throw it away.