It once required the smartest people utilizing resources from the wealthiest nations. 80 years later North Korea is making a pretty good effort. In another 80 years do you think it's unreasonable to think a wealthy individual might be able to build something?
In other words, why would building an nuclear weapon not get easier?
> In another 80 years do you think it's unreasonable to think a wealthy individual might be able to build something?
They'd not be able to do it without the weapons grade material. The matter of getting that stuff isn't really a secret, it's just pretty expensive, takes a lot of time, and will be noticed by intelligence agencies. I don't see why any of that would change.
The list of suspects will be short; anybody trying to refine U-235 would need huge quantities of natural uranium and a warehouse full of precision centrifuges. And anybody trying to create Pu-239 would need a nuclear reactor.
In other words, why would building an nuclear weapon not get easier?