Sick of it all
Why do people pay money for a pet from a breeder, or worse, a pet store?
How can they live with themselves, when they go home, knowing that their local shelter has animals who will be euthanized when they can't find homes for all of them?
By paying the breeders, they cause them to breed more animals.
By not adopting shelter or rescue animals, they cause them to die.
By not spaying or neutering their own animals, they create the potential for more animals to be born, who will not find homes, or who will take homes away from older animals in need. (Not to mention the very simple fact that they will basically cause their own pet to die from cancers of the reproductive tract.)