Ukraine is evidence that you're not a sovereign nation unless you have nuclear deterrents. Giving up their nukes based on a promise from Russia and the US is the stupidest thing they could have done. All the "major powers" keep proving that nukes are required or it's just a matter of time before the land looks ripe for taking or a "strategic regime change" is in order.
Last month Trump threatened to destroy the Iranian civilization. Doesn't this threat precisely give Iran a reason for wanting a nuclear weapon? I have a link to an April 7th article quoting his threat in th url above. I admit I did not think of this logic, I saw an article saying something similar the other day, but I can't find the link.
Iranian leaders already wanted a nuclear weapon before that threat so nothing has really changed. It seems the USA and Israel intend to just keep bombing Iran periodically, making it much harder to develop such a weapon. Iran may accomplish it eventually but when they have to do everything deep underground and the supply lines keep getting destroyed that slows everything down. I'm not claiming that this is a good strategy, but in purely practical amoral terms it's at least somewhat effective.