You also have to consider the other points Parenti makes. Every time the US escalated and the USSR had to play catch up, it was a burn on valuable resources for the USSR. They employed everything they could think of to burn down the USSR, both militarily and economically. Making more, bigger, better nukes, had the bonus of doing both I would imagine. Not to mention you are bringing the logic, of caring about life in general, to an equation that involves the US oligarchy. These are people that only have one thing in sight, absolute domination and ownership. I have no doubt a decent number of them had/have the mindset of "if I can't have it no one will." In addition, I'm sure some private military contractors were making a lot of money off all the construction that goes into making nukes, bases, submarines, etc.

So make more bombs, spend more money for our military contractors, build more bunkers and submarines. Force our targets to have to burn more of their own resources. This is what I imagine their thoughts processes were back then. Idk about now. I haven't kept up with what we have been doing with the nuclear stock pile as of recent.

We can argue about why make so many and that it doesn't make sense but none of that really matters because they did it. I'm just trying to give a hypothesis of what the reasons may be.

I'm sure at some level (setting aside the obvious desire to funnel public money into the MIC) there's planning for how future technology might make parts of the nuclear arsenal obsolete, and redundancy built in to compensate.

Missile interception is incredibly difficult now, but in 10-20 years? Submarines are undetectable now, but in 10-20 years (see the recent post about China developing new sub detection tech)? At least through the very limited lens of nuclear planning it makes some sense to give yourself different options to be flexible in the event one part of your strategy can be effectively countered at some point.