Following your reasoning, it makes sense why North Korea was able to produce a small amount of it in a relatively short time. They were well funded thanks to the left-leaning South Korean administrations from 1998-2008 who practiced Sunshine policy. The last bit is that they certainly want it bad enough but have failed to produce a nuclear weapon with significant power (nothing in the range of WW2 nuclear weapons). So if a country that wants it so bad like North Korea have been able to produce a controlled nuclear explosion, why can't they produce anything significant enough to be recognized as a nuclear state? The only thing that would stop them seems to be either expertise or lack of key material or perhaps lack of monies.
Producing some kind of nuclear explosion is mostly only about procuring the raw materials. Getting to significant yield is the actual hard part as it involves precision machining, measurements and timing.
Machining heavy metals is complex problem in itself even without requirement of extreme precision. It is hard to procure machining equipment with sufficient precision and tooling capable of machining hard metals without raising lots of red flags.
Almost anything that is capable of switching of significant powers with small or repeatable latency is essentially non-exportable with the reasoning that it is not useful for much else than triggering nuclear weapons (one could think of lots of other applications, but the devices are too bulky and expensive for most of them).
This is off-topic, but the agreement between North Korea and the US was made in 1994 (well before there was any "left-leaning" president in South Korea), in which the US agreed to pay for two Light Water Reactors in exchange for the North Korea discontinuing its nuclear program[1].
As expected, South Korea ended up funding most of the cost, while both the US and NK violated the agreement in numerous ways until the deal completely broke down in 2003. The reactors never saw the light of the day. Bummer.
There's a story (not sure how much of it is true) that, shortly before the deal, the Clinton administration went within hours of air strike on North Korean nuclear facilities, while Seoul was completely left in the dark. The realization that South Korea was essentially reduced to a spectator (and a deep pocket) in NK-related matters doubtlessly affected the two following administrations' policy toward North Korea, trying to have at least some of our own leverage. ("The US will take care of us" is not a strategy.)
But we get to blame our "leftist" presidents for their nukes. Niiice...
> Terms of the pact and consequent agreements included ... In exchange two light water reactors would be constructed in North Korea by 2003 at a cost of $4 billion, primarily supplied by South Korea.
In the case of North Korea it is likely the raw material they lack. They are a small and insular country, and may not have any significant indigenous reserves of uranium ore.
This is a very good thing, and unfortunately one that sea-water extraction technology--which is otherwise a very good thing because it makes natural uranium a renewable resource--may eventually have an effect on.
