I would consider buying a pet over adopting for the following reasons...
- certain types of pets aren't always available to adopt.
- they may only have aggressive dogs at a shelter
a few other reasons that other people may point out..
- if you want to breed, you can't adopt because they make you get them fixed
- the dogs may no longer be puppies
- people may only want pure breeds.
I have done both. I have a dog that we adopted 7 years ago. And I really wanted a chihuahua which are hard to find to adopt. I had to find a breeder in order to get him.
I will say that I hate pet stores that get their puppies from puppy mills. Because the dogs are treated poorly and it breaks my heart.