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.
Yes, I do agree that this is a form of cruelty and animal abuse. So I'm against this kind of sports, although I fell into horse racing, which to some extend is also animal abuse, but deaths doesn't not happen in every race. Unlike in cockfighting that it's either both or one of them are killed in front of those bettors and they are celebrating the death of an animal as a form of winning to them.
So maybe to each it's own, but I guess if we talk about morality and ethics in this world, animal cruelty is one hotly topic. We could enjoy gambling by not involving this animals and still win some money.