Being a vet isn't all cuddly puppies and kittens. You have to also deal with death too. There are times when an animal WILL die under your care, or an owner requests them to be put down for one reason or another, usually cost of care or the like. Its then that people skills are required. You have to be able to tell the owner in the nicest, gentlest way possible that their beloved dog or cat or whatever, is no longer alive. There are days when you'll come home crying, depressed, and want nothing more than to crawl in bed and forget everything that happened.
Sometimes animals will come to you bloody, and mangled and still alive. Then you'll have to be the one to piece their tattered bloody body back together and try your hardest to keep them stable and alive. Sometimes it works, sometimes its better to humanely euthanize them. You will be taking the lives of animals one way or another, so get used to it. Find a way to deal with the death. Because its going to happen, with you as the main caregiver to that animal.
Why then, do people become vets if its so depressing. Because there are days when a dog, who had a slim chance of pulling through, does the incredible and starts to pull through and makes it when all conventional medicine says he shouldn't. There are days when you'll WILL be playing with cute little kittens and adorable little puppies. There are days when owners will come to you, with tears of gratitude in their eyes and thank you about a million times for saving the lives of their beloved pet. That is why being a vet is worth while.
“The day the power of love overrules the love of power, the world will know peace.”
― Mahatma Gandhi