Why does Cat Like to Sit in High Places?

Here are some theories:

Height can indirectly be a sign of status. If there are multiple cats in a household, the cat who controls the best perches is generally the most dominant.

The highest cat is literally the "top cat". The height gives the cat a better observation point. From that location, the cat can survey his "realm" and be more aware of activities of people and other pets. In the wild, a higher place may serve as concealed site from which to hunt.

One of the reasons cats like the top perch on the cat tree is that the tree is located near a heat register, and the top perch is the warmest spot. The tops of refrigerators also tend to be warm.

If a cat is anxious or afraid, a high perch may get him further away from the cause of his anxiety (e.g., a dog). Why your particular cat seeks higher places may be a combination of these theories, or something only he will ever know.