Why are some attracted to violence?

So Tim is showing me his pics from his last trip from the Phillipines, and photos of a cock-fight come up on the screen and he starts describing enthusiastically how they tie the razor blades on the legs of the rooster, and telling me how they sew the birds up after the fight, all the time he's getting exited about it. It was really ticking me off. I don't approve of using animals in a blood sport as for entertainment. It barbaric, and ruthless. I can't see how anyone can call that fun. We might as well go back to the Roman days and watch the bloody battles between the gladiators and the bulls and tigers.