Do you consider murdering a thousand people you don't like to be better or worse than letting ten thousand randomly-selected people die because you can't be arsed to do anything about it?

It ought to be better. None of the factors of either option (murder, don't like, allow to die, randomly-selected, death due to apathy) are worth more than one human life. Thus, it is a simple question of scale. All the possible consequences - such as 'now people will be afraid if I don't like them', 'well, I can't be held socially or legally responsible for their deaths' - just do not outweigh 9,000 human lives.

That said, if I ever encountered this situation in real life, I would be immediately convinced that I had made a mistake in my reasoning, and would spend as much time as I possibly could looking for the alternative where nobody dies.