The reasons why cats like to sleep on chairs:
1. If the chair where the owner often sits has the smell of the owner, the cat will like to sleep on it very much. Makes it feel reassuring.

2. If the chair is very soft and the cat feels more comfortable, he will be willing to sleep on it.

3. When the weather is hot in summer, cats will look for a cool place to rest. Sleeping on a chair can make it feel cool and comfortable.

4. Cats like to stay in relatively high places and are not easily attacked. Sleeping on a chair can make them feel safe.

5. If the owner has no time to play with the cat, the cat will want to stay in a higher place to observe the owner.