This is a topic which has been discussed here before, by the way. You could have found about what we all think about cockfighting by using the search feature of the forum, but anyways...

I believe cockfighting to be some kind of animal abuse, not only because people are forcing to animals to fight to death, but also because in many occasions the cocks are held in very bad conditions, specially if they are not animals with a high degree of victories or a good lineage. I have a cousin who used to be quite involved into cockfighting, he would spend much money to import a cock directly from Spain, and I remember an occasion when he executed one of his losing animals right on from of us (I was a teen),  because it made him to lose money at the fighting pit.

It is better just to stick to casino games and betting in sports, where no animal is suffering severely.