Any Nihilists here?

[FrustratedFool]

Cat is just an agreed upon term to refer to a physical object and carries no ought with it.

But wrongness isn't a physical thing, cannot be measured, and carries an injunction.

They are not the same at all.

It seems you are trying to use bad as a direct synonym for harm. But that runs into a problem which names for objects doesn't, the ought/is problem.

Let's take your synonym and just replace bad with harm and vice versa.

With that acceptance, we can now agree that harm/bad is now something physical and measurable. But the question just now changes to: Why should I not cause harm/bad? Note this is a meaningful question, unlike Why should I not cause cat, which is nonsense.

So, why should I not cause harm/bad?

Edit: Additionally, why should anyone accept your belief that harm=bad? Without a shared physical object we can all measure/test, why not believe bad is something else? It seems arbitrary and subjective.