Even with responsible pet owners, who believe they're doing everything they can to provide a good environment for their pets, animals can escape. If the owner passes away, the next owner may also not be as responsible as the first. It's safer to avoid allowing potentially invasive species as pets. I actually really like animals, but I couldn't see myself ever visiting a breeder or pet store of any kind. If I lacked allergy problems, I would probably try to lure feral or stray cats into adoption. Many of them can be quite friendly if you're calm around them and don't force them to tolerate petting. They don't typically come as far as my area though, presumably due to the coyotes and occasional feral donkeys. I don't particularly like the pet trade though, so I wouldn't want to support it but rather provide a home for existing animals that require one.