In the end, though nazis didn't value non-arial lives, they were no idiots. Why would they destroy cities and pollute areas supposed to be the part of Reich? The end of the world is both hard and unprofitable. "Nazis would" is a scary tale nicely covering the actual face of war that always remained the same.
What is really scary today is that some countries develop supreme air/space control systems, so those in the club become immune to any sort of dialog.
There was no economic in V1 and V2, yet they did it, harming themselves economicaly more than they harmed the targets.
Additionally they knew losing WW2 is existential threat for most of them. If they could destroy London with one push of a button - they would.
Nukes at the time were still weak weapons. You could inflict a lot more damage (and a lot more damage happened on Tokyo and many other Japanese cities) by regular firebombing. You did not need nuclear bombs to inflict catastrophic loss of life.
Now when it came to thermonuclear weapons, the magnitude is entirely different, but that only occurred many years later. It would never have occurred at the time of WW2.
If even the US government couldn't resist obliterating 2 cities in Japan with Nukes can you imagine what the Nazis would have done? There would have been zero consideration for the loss of human life, possibly large areas of continental Europe and the US would have been bombed.
I think "the world did not end" meaning "it never will despite what's been said and done in the past" is a really dangerous miopic notion