Farms take up massive areas so farmers can not live in cities. Natural resources like minerals are unlikely to be located close to major population centers, so

Farms take up massive areas so farmers can not live in cities. Natural resources like minerals are unlikely to be located close to major population centers, so miners can not live in cities. Between population centers there must be people maintaining the transportation infrastructure, these can not live in cities. All of these people who can't live in population centers need various services, the providers of which also can't live in cities. The people in rural areas are overwhelmingly there because they need to be. People want to live in urban areas, it's a real problem that people leave rural areas despite the need for their services, and thus the rural communities are no longer capable of providing good quality of life, leading to even more people leaving until only those who can't escape remain. If the communities providing resources to the cities collapse, what happens to the cities?