All Empires fall, all Societies fall, its human evolution, I believe that the more civilised and more decadent a society gets the quicker its demise. I believe that people looking for some single spectacular event leading to the collapse of society is most unlikely. Its probably going to be multiple interlinks events.
I see modern western society entering ( already has) a terminal downward spiral of failed economic policies, ever higher taxes to fund ever more lavish welfare or infrastructure projects which encourages more people with a sense of entitlement and a government system trying to meet those growing demands.
They either raise taxes or cut public services or both, either way more people want to take out of the system but less think they should pay into the system. Leftes will raise taxes then waste the extra revenue, Righties will respond by isolating themselves even more, throw a few wars, terrorists, bad luck, recessions into the mix and you have all the ingredients of a perfect storm.
ALL Western nations face growing populations and a growing percentage of that population is getting more dependent on welfare, plus the wealth creating baby boomers are getting older they want the pensions they paid for. The ruling elites can see the writing on the wall sooooooooooooooooooooooo what do they do?
Well one option if if they know that the National debt is getting out of control, unchecked migration is getting out of control, government spending is out of control, demand for welfare is growing out of control ( especially from those who never paid in to the pot in the first place). They know civil unrest and crime is rising, they know it takes less and less to trigger a riot or mass shooting.
The rich, powerful , influence, social elites want to ensure THEIR continuity but HOW?
BY SOCIAL ENGINEERING That is how.
They begin by centralising essential services such as schools, hospitals, libraries, universities, big business, etc into the cities. They start to withdraw or relocated the public officials from the rural areas into the cities, they encourage the masses to move into the cities with promises of affordable homes, better healthcare services, better law enforcement, cheap public transport. If they have to spend tax payers money they focus the spending on cities making it ( on the surface) become ever more attractive and appealing to the masses, so URBANISATION happens ever faster.
What happens when the bulk of the masses are living in the cities?
(1) Well those in charge find they now control the flow of FOOD, WATER, UTILITIES, MEDICAL SUPPLIES, FUEL, PUBLIC TRANSPORT, COMMUNICATIONS, MEDIA, LAW ENFORCEMENT and the INTERWEB into the city............................................... They now control the essentials of LIFE and the HOUSING and the JOBS.
THEY NOW CONTROL EVERY FACET OF EVERYONE'S LIVES, this leads to
(2) They have now depopulated the RURAL areas only farmers ( usually now owned by big corporations) and other essential rural industries, that leaves the nice low population, low pollution, low crime green and pleasant bit for THEM to live in.
Then when the collapse finally happens all the eggs that are going to be broken in in a few concentrated Urban conurbations and the wise, the prudent, the rich (and the preppers hopefully) can survive in splendid isolation until things start to get better.