Eh, it's also clear that nations without nuclear arms exist at the whims of great powers, particularly now. "behave and we'll let you have some prosperity unless you need defense in which case good luck" isn't exactly a strong argument.

And the people in power in Iran actively are not in favor of the good of their people, a large proportion of which want nothing to do with their religious fundamentalism.

How do you convince oppressive zealots to play nice for peace when their whole existence rests on having enemies? "death to America!" being the popular chant at political rallies.