It gets complicated, honestly. Who to save and who to rid the world of?

I realize I'm biased, being a vampire myself, [ or close enough to one that the distinction doesn't matter ] but those vampires were attacking people for blood, and worse, turning people against their will. There are plenty of willing donors if they had only thought to ask.

I had no problem killing a vampire who was attacking someone for blood. That's not trying, that's taking.