It really depends on the chinchilla, each have their own personality. There personalities are really all over the map just like humans. Some chins prefer a friend(s) while others prefer to be alone, and everything in between. I've had some that like playtime with other chins, and/or live near other chins, but don't want to be housed with another. In the wild they live in herds, but then they are also able to get away from each other and pick who they want to live with. A single chin is perfectly fine alone so long as you give it attention every single day, like you would something like a parrot.