Back-of-the-enveloping it I have a hard time seeing how you'd arrive at more than low-100's of exabytes total storage across the world's supply of cellphones --

Back-of-the-enveloping it I have a hard time seeing how you'd arrive at more than low-100's of exabytes total storage across the world's supply of cellphones -- there's 1.4 billion active iPhones and 3.75 billion other phones, so even if you assume that the average iPhone has 32GiB and the average non-iPhone has 16GiB (which is pretty generous considering a large chunk of those are probably feature phones), you only get up to ~100 EiB. To break 2000 EiB you'd need each cellphone to have more than 400 GiB of storage, which I'm pretty sure is very much not true, unless my phone is older than I thought it was.