“ The point of a nuclear bomb for a country like Iran (or Pakistan, or North Korea) is deterrence”

I hope this is true, but Iran has a hard time convincing people because their theocratic elements are suicidal from a secular standpoint. Eg their religious messaging is confounding.

You are lumping together three very different countries into a western mindset of deterrence.

While Pakistan is Muslim they are not the same as Iran in any way. The current rulers of Iran do not operate by western logic and would be consider a "holy death" as a direct path to heaven.

Iranian populace isn't behind that, the people themselves are reasonably secular and aren't behind that. However, the leadership is dangerous and you should not assume they would use western logic.

This is where the logic stops.

If Iran is going to behave logically with a nuke, then why is it so terrible for them to have one? If they are illogical, then why would they NOT choose to wipe out Israel and blow up a couple major US cities?

The arguments I hear about Iran are almost completely contradictory.