It's true that the way people choose to present and promote a gambling activity can actually have a enormous influence on how people view and perceive it.
Both cockfighting and lottery are both Gambling that can have almost effect on the gamblers involved but lottery gambling is often promoted as a fun way to potentially win big prizes, while cockfighting on the other hand is often associated with violence and illegal activity. And just as you mentioned, both gambling activities could have negative impacts on the life of the gamblers.
Why will someone put to innocent animal in a cage to fight each other and an individual with his correct senses will go to watch this happen and also bet on which of them will win. Will you bet on two humans that are put in a cage to fight and kill each other. Any type of gambling that has alot of violence involved and isn't sport related that's govern by a set of rules shouldn't be something we should be betting on as with our bets we're encouraging the organisers to continue.
Individuals have a different perception of gambling operators when what they're promoting are different regardless of both of the promotion being a gambling activity. Animals have feelings and we shouldn't see them as things to put into cages for our pleasure. There are many things that we can use to gamble and it won't have to involve endangering any individuals or animals through fighting in cages, unregulated.