Ideally, the world would be a better place without weapons of mass destruction but recent history seems to be making that less likely. I don’t know how a leader of a country without a powerful ally could look at the last few years and decide giving up their WMDs was in their best interest.
Saddam Hussein did get rid of his WMDs, even though we spent time trying to cultivate some mystery about it as part of regional politics – and he still got his country invade by the United States.
The United States convinced Muammar Gaddafi to give up his WMD and we reward him a few years later by using military force to help in his overthrow.
Finally, we have Ukraine which was a good global citizen and gave its nuclear weapons to Russia in 1996 as part of the Budapest Memorandum. Now a key portion of the county has been seized by Russia in clear violation of the agreement. It seems like the person with the bigger nuclear stick gets to say what the agreement really means.
At the same time the Kim family in North Korea remains one of the worst actors in the world but they have nuclear weapons and remain safe. Given recent history I don’t know how you could convince anyone in the top leadership of that country they would be personally safer without them.