Cities provide concentration of services that people need. No city, no services. They also provide concentration of jobs, and concentration of people. For an extreme example you can't have the full set of services for 1 person in the middle of nowhere without an impossible cost.

So it all depends how independent you are from everything and everyone. If you have complex medical needs or need to be around certain people also in the city, you might have to live in the city.

Homeless and mentally ill get treated by programs and services that can be afforded by major cities (small towns apocryphally throw homeless on a bus to the big city to fix their homeless problems).