I'll certainly agree that North Korea's practical and capable threat level is very much exaggerated. But I do think their leadership could be deranged enough to do it if they could.

Russia, admittedly, would probably stand to lose the least by pressing the button. At least assuming they received minimal retaliatory response.

That's not to say that I think their leadership has a lot of interest in such action. Mostly just pointing out that their nation could probably manage just fine without US or Western trade compared to most major powers.