Perhaps accidentally stepping over the line is the most likely use scenario.
Nuclear weapons in the modern world are useful deterrants, and that's it: a dictator with nuclear weapons has no external enemies they could consider targeting without guaranteeing total annihilation in response.
The one exception here is that using a nuclear weapon on your own country and people might be a useful exercise of power...but even then, it's abundantly clear that the most likely outcome is still total annihilation - the world won't tolerate a nation lighting off nukes against targets in it's own borders much either.
Why do you think so? Famines seem to work just fine within borders.
I'd argue that nuclear weapons are no less safe in representative democracies. The only country to use nuclear weapons against another nation was a representative democracy. The only country to use nuclear weapons against another nation multiple times was a representative democracy. The only country to use nuclear weapons against civilian targets was a representative democracy.
MAD is still going strong. It's not military based, but economical.
It's the reason why theories about intentional release of COVID-19 are bunk.
China is worse off than it would have been without the virus.
Same goes for nukes. If Xi or Putin decide to nuke the US , people will assault their palaces in 3-6 months for food and water. Even if the US somehow fails to respond.
The global economy is interconnected to a degree that makes it impossible for a leader to order a nuclear attack and not have his own people remove him violently
Only if you measure progress in economic terms. Nothing I've seen contradicts my belief that they are now geopolitically better off than before the pandemic.
Quality of life of the population
If you leave quality of life on the table because of geopolitical games you are shooting yourselves in the foot.
Even during massive state sponsored hate campaigns (such as the one promoted by Hitler against the Jews) the population spends just a bunch of minutes per day actually fuming and hating...the rest of the 24 hrs they live their lives.
Quality of life is a much more potent motivator to support the leader/party than hatred.
That's why any sane country and leader would never attack an economically important country intentionally.
Violent wars are relegated to Africa and the economically unimportant areas of the Middle East such as Yemen. With some small outbreaks here and there in ethnically hot areas such as Ukraine
MAD policy appears to be effectively over, or at least there is no longer any mention publicly, perhaps it is just assumed. While it can appear crazy, hence the name, it was a rather ingenious way to solve the problem, albeit we know now we have come dangerously close at times, at least we knew the risks and the lines that had to be crossed.
The next point and somewhat related is the change in nature of nuclear weapons. The variable ability of tactical nukes to change their explosive size, has resulted in a modern range of weapons that aren't as destructive as their elder brethren. It may seem like a good idea but the issue is it also opens the possibility of their more active use. A state may consider it acceptable. This could result in the reverting to an older policy of nuclear weapons. The MacArthur plans to use them in active combat, it becomes too easy to dial the Nuke down, target a military base and say "sure it's ok it's a legitimate military target".
That to me is the danger in the modern world. Attitudes, at least Western are still as a weapon of last resort but I can't predict the future and say that will always be the case or that other nations will share the same sentiment.