How are those things even related? The US has lots of munitions, because US goodwill is the reason Iran isn't glass? That's a complete non-sequitur.

The US's stockpile of conventional precision munitions and the US's nuclear arsenal are two very different things. The depth of one has little to do with the other.

The US hasn't run out of precision conventional munitions, but it is running low. There's no reason this should come as a surprise. The US has been fighting a medium intensity air war for months without making any move to ramp up production of those munitions.

The reason Iran isn't glass is because doing otherwise would be a global catastrophe, and even the assholes in charge don't want to go down as the worst mass murderers in human history.