Somehow each house cat has its very own human to feed it, pet it, supply a warm dry home, let it in, and let it out. In return the cat occasionally deigns to purr. This is a better schtick than other domesticated animals get, the others have to work for a living or get served at table as food. Cats don't have to put up with any of that.
The other weird thing about cats. Flash photography of humans often leads to "red eye", where the camera sees the eye as bright red. In cats we get "green eye" instead. My digital camera has a red eye correction feature built in, but nothing for green eye.
The first thing (close association with humans) clearly has survival value. The second, green-eye, is not so obvious.