Thanks for the comments!
I’m especially keen to explore bottlenecks (e.g. another suggestion I saw is that to reach 1 billion a year would require 10x current global lithium production to supply the batteries.)
A factor of 2 for increased difficultly due to processing intensity seems reasonable, and I should have thrown it in. (Though my estimates were to an order of magnitude so this probably won’t change the bottom line, and on the other side, many robots will weigh <100kg and some will be non-humanoid.)
I’m open to that and felt unsure the post was a good idea after I released it. I had some discussion with him on twitter afterwards, where we smoothed things over a bit: https://x.com/GaryMarcus/status/1888604860523946354