> As parent said, I'm sure people made the exact same argument about IPv4 back in the day, but comparing it to something else.
You're ignoring the sheer scale of this question. We don't have enough raw materials on this planet, or likely in the observable universe, to produce enough devices that would consume that many IPs.
We could colonize 1 billion planets.
Each of those planets could have 100 billion people.
Each of those 100 billion people could own 1 billion "things" that could be considered "networked devices".
Each of those "things" could consume 1 billion IPs.
We could have all that, and we would still have 70% of the IPv6 space left.
> The decision to put a 32-bit address space on there was the result of a year’s battle among a bunch of engineers who couldn’t make up their minds about 32, 128 or variable length. And after a year of fighting I said — I’m now at ARPA, I’m running the program, I’m paying for this stuff and using American tax dollars — and I wanted some progress because we didn’t know if this is going to work. So I said 32 bits, it is enough for an experiment, it is 4.3 billion terminations — even the defense department doesn’t need 4.3 billion of anything and it couldn’t afford to buy 4.3 billion edge devices to do a test anyway. So at the time I thought we were doing a experiment to prove the technology and that if it worked we’d have an opportunity to do a production version of it. Well — [laughter] — it just escaped! — it got out and people started to use it and then it became a commercial thing.
- https://www.youtube.com/watch?v=mZo69JQoLb8&t=816s
They were contemplating 128 bits addresses all the way back then, but settled on 32 bits as a mere proof of concept that got out of hand.