You have zero understanding. Iran started its nuclear program under Shah with US and Israeli partnership. The smuggled parts, blueprints post revolution came during late tenure of Khomeini who was aggressively pursuing the program. Result of this, as per Israelis and US, Iran could field out nuclear weapons (deployable warheads) in 90s, read project Amad papers released by Mossad and CIA. They assumed Iran had somewhere around 5-10 devices with ready multi-entry neutron guns installed on them, to be fitted in RV of now retired Shahab-3 MRBM.
Khamenei politicized the program through Ahmadinejad when he allowed him to threaten "annihilation of Israel", attracting global Jew and their controlled west's animosity towards Iranian nuclear program. This was a deliberate move to make sure Iran will never get nuclear arsenal. Why did he do that ? conspiracy theorists will say he hates Iran and there is some truth to it as he said during the war that Iran is not important. But, there is another more visible angle to it as well. IRI served its purpose and was already dying as a faulty political idea at start of 2000s. Khatami-Clinton breakthrough was immense and Marg Bar Amerika slogan had less meaning anymore. Baathism was no longer a threat either. Khamenei's IRI (including his hardlienr gang) needed something to rally people around them for political survival and nuclear program served that purpose just fine. I mean he could have penalized A-nejad for his annhilation threats to another country but instead he frauded the elections to get him selected again. Iranian nuclear program could have delivered WGU in Amad devices silently while maintaining Khatami like friendly approach towards west but instead they refused to weaponise yet kept the threatening posture so that (A) local population rally around them, seeing them as saviour of Iran. SIlent nuclear armament wont give them that legitimacy (B) Regime can play the blackmailing card against west which it successfully did for 25 years. Whenever they wanted, they would say shit against US and Israel and then Khamenei will push liberal reformists dous of Rohani-Zarif and Pezeshkian-Aragchi to talk with west. He had ZERO and I mean ZERO intention of strategically arming of Iran at any point.
What stopped IRI otherwise from pushing HEU to WGU ? IRI-8 is one of the worlds most efficient centrifuge design. Fakhrizadeh himself patented IR-2/3, IR-4 and later 4M, the highly efficient C-fiber design native to Iran, thats 1990s and early 2000s. If weaponisation was the intention they could have shut Ahmadinejad's motor mouth and quickly installed hundreds and thousands of IR-4M, IR-8/9 for WGU. IRGCASF has worlds class delivery system I men but the real focus was using nuclear program as a baragining chip for regimes survival and nothing else.