well firstly i don't see how your math works (e.g. if it take 100 people each working 35 hours a weeks to support 100 people, wouldn't it also take 10000 each working 35 hours a week to support 10000 people? the need for resources and the amount of people are proportional), but also, my main issue with a large scale was the need for industrialization. in small communes, industrialization isn't particularly necessary, but when more people join it is, and i don't see how you will achieve that