Can you imagine Harry killing Hermione because Voldemort threatened to plague all sentient life with one barely noticed dust speck each day for the rest of time?

I think I see here what's wrong with your thinking. "all sentient life", which is what would be plagued with dust specks in this example, is incredibly, inconceivably, astronomically less than 3^^^3. Actually, it's even worse than that. It's incredibly, inconceivably, astronomically less than a googleplex (10^(10^100)). And that is incredibly, inconceivably, astronomically less than 3^^^3. Actually, no. You can add a vast number of levels before the difference between one and the one a step higher up can be accurately described as "incredibly, inconceivably, astronomically less".

From what you have written, it seems you have not internalised this. We are not talking about a trillion dust specks, a quadrillion dust specks, or a quintillion dust specks. There is a difference. A large difference.