The first strike could well be first strike doctrine - empty your arsenal to prevent as devastating a response.
The idea that we’d somehow survive a nuclear exchange unless we were in Africa is crazy
I’m fact youd probably not want to survive
You fundamentally misunderstand the principle of mutually-assured destruction, and this has been apparent from the first mention of it in this thread.
It is impossible for either Russia or the USA to eliminate each other's capacity to launch a retaliatory nuclear strike, meaning that whoever launches first will enjoying "winning" for about three minutes before they themselves suffer a couple hundred nuclear explosions.
If memory serves there are a couple of forum members with experience serving on US submarines. They will confirm that even if Russia somehow took out every land-based nuclear launch site on US soil in some sort of sneak nuclear attack, the weaponry aboard the US missile boats is more than sufficient to destroy Russia.
That's what MAD means. It's the end of the world the moment the first launch is detected. It's not a trump card that guarantees Russia wins, despite your misguided belief to the contrary. Indeed, the same holds true in reverse - the US lacks the ability to wipe out the Russian retaliatory capacity, so if Biden decided to push the button Putin can do the same before the first American missile lands.