I have a 5lb yorkie-poo... I don't think it's selfish because he was bred to be a pet, there is no way he could survive on his own. Maybe breeding animals as pets is selfish, but I believe he has a good life with me. He has a nice big house and yard to run around in, all his meals are provided. We play all the time, he has three beds and sleeps pretty much whereever else he wants. When I am at work, I keep him in the kitchen with a pet gate... Its not a huge amount of room to run, but his toys are in there and I leave the blinds open so he can bark at things during the day.
Also I think he likes being with me because he gets sad when I am not around or if I pretend like I am going to leave him outside.