system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why it takes so many years for a county like Iran to build a nuclear weapon when the technology has been around for over 60 years?
gpt
eli5: imagine you are at school and little billy has made a paper crane. his friend johnny also knows how to make a paper crane, and they make lots of paper cranes together. they didn't tell each other how, and they didn't learn from a book - they just kind of figured it out one day, trial and error.

so now you want to make a paper crane. you're all jealous and crap, and paper cranes are awesome. there's just one problem: you don't know how. oh and there's another problem: billy and johnny know how, but if they told everybody how to make paper cranes they wouldn't be so cool anymore.

so you have to figure it out from scratch.

you know what a paper crane should look like when it's done, but you have no idea how any of the folds are done, in what order, or even what kind of paper you need to use.

the only thing you have going for you that billy and johnny didn't is that you can look at their cranes (not very closely) and see kind of what it should look like when you're done with it, but that's not very helpful at all.

replace cranes with nuclear technology, billy and johnny with nuclear powers, and "being cool" with guarding nuclear secrets.

* as an aside, a lot of the reason the nuclear powers don't share their technology with countries like iran is that those regions are incredibly unstable, and all it takes is one rogue officer to hand off some u-235 to a terrorist faction and you've got a dirty bomb unaccounted for. it's bad news bears! honestly! there are really not a lot of scenarios that are worse than the idea of ayman al-zawahiri in possession of a nuclear device. and literally all it takes is one bad decision to go from "iran has a nuclear power program" to "iran doesn't know where some of its uranium went."

* another interesting point is that, although i can only speculate on figures and any cases i could cite would be anecdotal, but a lot of talented nuclear physicists from third world countries end up coming to developed powers and not going back. it'd take you a while to develop nuclear technology too, if all you had was second-string nuclear physicists, amirite?