> that most countries that want to become nuclear powers aren't able to do it

How do you know this?

The thing is that most countries don’t want to become nuclear powers because there is a carefully setup and maintained set of incentives against it. This involves both carrots (you get good things if you don’t want nukes) and sticks (bad things happen to you if you do want nukes).

This set of incentives failed a few times and that is how we got nuclear proliferation. Almost everyone who wanted nukes enough despite this set of incentives were able to do it.