Why cats like to crawl into boxes:
1. When a cat is scared in a new environment, it will hide in a small space to make it feel safe.
2. When cats are anxious, they will crawl into boxes to regulate their emotions and relieve stress. 
3. If the temperature is too low and the cat feels cold, it will also like to crawl into a box to keep warm.
4. Cats are very curious and will crawl inside to see what's in the box.
5. When cats get bored, they will also kill time and find fun by crawling into boxes.
