That 80% consumption rate is too high. Way too high. For a civilisation to ever have. I doubt that a civilisation of any kind, ever, period, could have a consumption rate of 80% and survive. Why? Well, because civilization is made of investments. The idea of civilisation is about investments — collective ones. The Greeks had the agora. The Romans, the forum. Even more ancient civilisations had canals and waterways and temples and roads and farms and so on. Civilization is about investing, together, in things that raise living standards for all.