The main point of having nukes is not using them. The moment one uses them -- they lost.

Nukes are good as a deterrent, not good as a weapon.

People are just fear mongering to suggest Iran would use them or give them to those who would. The real issue here is that once you have them, you basically entrench yourself as a regional power. If the regime started falling out of favor, all their neighbors would be obliged to come to their aid to protect the nukes. Also, you would be far more limited in how you fight your proxy war. These are the things the involved parties are considering, not Armageddon fantasies.

Same reason the U.S. and USSR were afraid of each other in the Cold War.

There's "having nukes" and there's "using nukes".

https://m.youtube.com/watch?v=QgkUVIj3KWY

The trouble with a regime like Iran is that they are a death cult. The price the put on human life (their own people as much as anyone else) is low, and they're all for martyrdom. With Iran, you cannot assume it's a just a deterrent in a cold war. You have to assume an increased likelihood that they will actually use them.