Southern Comfort...there's no one quick answer to this one.
I love medicine, surgery, and animals, but have come to truly appreciate the people too. I guess the best way to explain it is my response to seeing a dead dog on the side of the road. Before I became a veterinarian, I mentally would think "Poor baby, he was lost and scared, and now he's been hit by a car". My empathy is not less now, but my first thought is "He's wearing a collar; somewhere somebody is worried about him, and will soon be mourning him." I grieve for the owners as much as for the dog.
I also like the idea of being able to empower the patient and inmprove patient compliance by including them in the health care decision process. You can do this to some extent in veterinary medicine, but like in pediatrics, it is not the patient directly. I think by educating people and making them responsible for their own health and treatment, you are vastly improving their quality of life.
The second reason is a little more on the practical side. I learned how to be a doctor and a surgeon in veterinary school, and yet I find myself a bill collector in practice. On the nights that I have call, I am handed a list three pages long of clients whose pets I cannot treat because they owe the practice lots of money. So then when they call, I have to decide whether or not to treat the animal. If the animal's life is endangered I always do. Then I'm in trouble with the practice owners the next day. If you don't treat the animal, the owners say "If you really loved animals, you'd treat them for free". What most don't realize is that over a third of my salary goes back to repaying student loans. I'm barely making it and I'm one of the better-paid folks in my class.
In addition, most of the treatments I learned in school I never get to use. Unless you're practicing in an extremely affluent area, you are begging people to get rabies vaccines and trying to defend the need for a physical. "The vet don't need to look at him. He's healthy, just give him the shot. I don't wanna pay for the rest of that crap." The worst part is, it's not just the uneducated that have this attitude. I have a client who's a physician that cried about a $15 office call/physical exam fee. She was dumbfounded when I asked her what she got for a physical exam, and immediately proceeded to tell me it wasn't the same thing. I would love to be able to practice where I can make decisions in the best interest of the patient and only have to justify costs to an insurance company, not every client that walks through the door.
Sorry for the long answer, but there's just no way to explain it in 25 words or less!