Hmmmm, I wonder what the Great American Buffalo would say to that had we not hunted it to extinction. We don't ask, we don't care how the cow feels about a Big Mac, we just take and take, and why? Because we can. That is nature. A cheetah doesn't ask a baby yak, a hawk doesn't ask a snake, and we don't ask the cow. So in nature, a species is preyed upon by another. Not in some benign manner, but violently and painfully. I would think that a Vampire hunting is exactly natural. You call it evil because it is hunting humans. Pretty sure the cow would call you evil for the same reasons.
The bible says thou shalt not kill. it doesn't say, thou shalt not kill a human. I guess in the end we are all evil. You may not have actually killed, but you certainly have reaped the benefits of it.