Hurting any living thing for pure enjoyment is a sign of some serious mental issues.
Eating meat is done for PURE ENJOYMENT
i.e. there is no biological need to do it, and in fact it would be a lot healthier for the planet if we didnt. But we feel it makes our life experience richer, and so we slaughter the animals in brutal fashion (watch one of PETAs propaganda videos if you dont believe me).
Similarly, biological research on animals is done because we feel that it will enrich human lives and human health. No lab rat is ever going to benefit from a diabetes or cancer drug that is developed as a result of experiments on animals.
Some people fight dogs because they feel that it enriches their life.
How are A and B ok, but C is vilified?
I've never been to a dog fight and never want to go to one. i dont really enjoy blood sports and even the NFL makes me nauseous sometimes. But i do however eat lots and lots of meat.
Further, I have also personally executed >50 mice/guinea pigs and have asked others to kill >>100 mice/guinea pigs for me. We breed mice that have no immune system and can't even grow hair, and we give these mice tumors so big they protrude out the side of the mouse. We do surgeries on mice and insert catheters into the portal veins of mice and rats so that we can add radiolabelled metabolites into these mice. We keep the mice alive for 3 days with these catheters and then kill them on the third day. Sometimes the mice pull out their catheters in the middle of the night and bleed to death slowly. Nobody is there to provide anesthetic in the middle of the night. The dying bleats of these mice almost certainly cause anxiety and alarm in the other mice.
Other labs do far more
disruptive interventions on primates.
None of the knowledge from these experiments will ever benefit a single lab animal.
Theres animal blood on all our hands (maybe more on mine than most people's...), thats why I dont point fingers at bullfighters or dog fighters.