I would point out that hunters/gatherers are much more dependent on weather than farmers. Hunters/gathers do not have the ability to store food against tomorrow. Farmers do it all the time. That food storage makes farming superior.
Consider a city in a third world hell hole. One rotten local government guy, and the city would be destroyed. Look at Zimbabwe, as a particular example.
How many disasters would have to occur to have a city in the US fall to that level. Even New Orleans, after a disasterously corrupt state government for over 50 years, after a disasterously corrupt city government for 50 years, even when it is 30 feet below sea level, and then taking a hurricane:
New Orleans is still there!
US cities are like government programs: they hardly ever die.
With less than half of the original population and many of them are 'living' very close to the edge, even now.