Yea but within a few hours they (nk) will cease to exist, I think to a certain extent people are under estimating that part of the equation, yes hundreds of thousands of South Koreans will die (imo it won't get close to the millions) but the moment that first missile hits the ground its over for NK and this won't be like the first, for many reasons.
I think you could be right that it'd be hundreds of thousands (I did some research and found the million SK casualties estimate repeated as well as pushback against it).
But North Korea does have a million soldiers, close to 10,000 tanks and armored vehicles, something like 20,000 artillery/rocket pieces, hundreds of missile launchers, 1,000 attack aircraft, and around 10,000,000 pounds of chemical weapons. And most of that is right on the border, 35 miles from Seoul. If they go full-crazy mode, their best bet is going to be a full-on rush at Seoul and the hope that half their massive army can make it there faster than anyone else can stop them.
I got homies on that border right now.