Iran's (leadership) actions toward many of it's neighbors are a big reason for concern about that country having nukes.
As much as they say they are not interested, their actions have shown otherwise. Cause for concern.
While they also may be sane enough to not use a nuke on another they can use it as leverage it via a proxy.
A problem for the right on this is their inability to distinguish between "Iran poses a threat to others" and "it's in our interests to get more by destroying Iran".
We could get rid of the Iranian nuclear threat immediately, if we removed OUR nuclear weapons, and others such as Israel did, removing the threat they pose to Iran.
So we're not blameless in this game, if our goal is to take it all, not 'peace and justice'.
There really can't be much question that the start of the nuclear danger is us.
Everyone else wants nukes because someone else has them, so they need them for their security. And the first and largest someone else is us.
It's a bit like the Cuban Missile crisis logic - it's ok for us to put nuclear missiles on the border of the USSR, but it's worth threatening global nucelar war for them to do the same.
And somehow we're the victim in that scenario. This is called the arrogance of power.
But that's how it plays out. We force outcomes we like not because they're fair, but because we have the power to do so.
Saddam was executed not for his crimes against his own people, a period in which we supported him, but for not doing as we told him to.
Sadly, many Americans today, I suspect, are happy if the US abuses our power to get results good for us around the world, with no concern for justice to slow that down.
I recall how those Americans dismissed the possibility of the US doing anything wrong with the immediate response simply of spouting a phrase, "blame America first!"
With that phrase, it became impossible for there ever to be a wrong done by the US for those people. No matter how wrong the action - "blame America first!" dismissed it.
For the US, there is no history of the US replacing Iran's democracy with a dictator for decades. For Iran, that history exists.
Rather, all that matters now is our weakening Iran - surrounding them with US proxies, massive sanctions and the denial of nuclear weapons for their own defense.
All of which leads to increasing demands they not arm any of our adversaries - while we continue to arm our allies - on pain of war, just as with Iraq.