>>508858044Energy is almost pure wealth, but we will never lack energy, that's the very unfortunate part.
Cities population can only grow because of movement from outside to the cities, it's been true since cities exist, people in cities don't make kids enough for population renewal.
The first problem is a city made for 1 million habitants can't function correctly with 900 000 habitants and it will collapse if it goes lower and lower.
The second problem is there's not a lot of people left to bring in the cities, hence massive immigration from Africa
Third problem is our system is (like all empires) purely stable if it grows : promises for the future are what keeps it going : we build housing, transports, for the (nearer and nearer) future even if we think it's overloaded, if you look at India, you understand our western systems are far from being overloaded.
So growth is more and more difficult to achieve, causing less and less growth until one city cannot grow anymore, then another one will follow because its wealth depended on maintaining the systems of other cities and it's all an house of cards.