If we can make 2 billion people 10x richer than they are today, market/economic growth is not necessarily capped at 10x. Systems don't have to be linear.

As a contrived example, I would imagine that folks living on $2/day probably buy on average effectively 0 iPhones/year. If somehow they had 10x the wealth they do now, they wouldn't buy 10x the number of iPhones they could previously buy... they would buy almost-infinity-x the number of iPhones they previously could buy, thanks to division by almost-zero.

BTW, my point is not that this is some kind of arithmetic trick, but that 1000x growth just depends on how low the starting baseline is (which is very low, by almost all measures of baseline economic activity/wealth of the $2/day demographic).

I agree that systems don't have to be linear, but for it to be non-linear, it'd have to feed back somehow. Simply buying X times as many iPhones doesn't do it, unless e.g. those iPhones allow them to be Y times more productive, etc.

My point of view goes something like this: some parts of the world _are_ developed, and these already have the various additional productivity multipliers we theorised about above. These can be the baseline productivity level for our calculation. So if the rest of the world were to be brought to this level, the end result is indeed linear, and more or less depends on where we drew the line for "developed". However, it is not 1/1000th of the world population. We could be talking about a 10, or maybe 20x multiplier if we're very generous.

I also don't think historical precedent favours such optimistic numbers, though we could be living in interesting times. However OP's point was, again, a simple introduction / upliftment of more people, not technological multipliers.

Also economic growth is still tied to finite resource consumption, so 1000x the economy would devastate the earth. Sure, humanity's economy may become decoupled from finite resource consumption, but that would be a profound change in life on earth.