Does anyone really think druggies and gang bangers are just going after each other and too busy for anyone else? These aren't generally folks with much consideration for others' safety or property.
And gangs "killing each other" doesn't get them out of the gene pool so much as it keeps them killing each other and screwing up life for everyone. Call me crazy, but I think it might help a bit if they stopped killing each other. And is "dam" gene "pool" a pun?