Definitely unsustainable has been so for.....1,000 of years. There has always been vast differences in peoples wealth. Why would anyone think it isn't sustainable all of sudden.
Existing societies accepted that's 1000 years occupied exclusively by civilisations that have grown, prospered and subsequently collapsed; usually with the involvement of significant economic factors. The core tenet of modern capitalist economic policy is that growth can continue unabated perpetually. Surely it's patently obvious that such a concept is fundamentally flawed, simplistic in the extreme and that all growth must eventially reach limits.
A few factors that will likely contribute towards curtailing this mythical perpetual growth upon which our great economic ponzi scheme is predicated:
- Falling reproduction rates - people are having fewer kids; due to falling biological fertility, reduced prosperity and reduced desire. Fewer people means lower economic activity and less money to pay for the upkeep of the ageing previous generation / pay off the debt they've incurred.
- Ageing population - tied into the above; thanks to the high reproduction rates of the boomer generation and their enjoyment of improved healthcare, we'll have an increasingly top-heavy population with a growing proportion of dependants relative to those who can provide for them.
- Falling prosperity - the current youth generation is the first in living memory to be expected to have a lower quality of life than their parents.
- Spiralling debt - both public and private: It's clear from the fact that both private individuals and entire nations are having to rely increasingly on growing amounts of debt just to maintain the status quo, the current system cannot continue indefinitely as it is.
- Totally dysfunctional economic system - the relationships and rules upon which the economic model were initially based have long since gone out of the window thanks to increasingly desperate, unprecedented monetary policy to try and prevent the house of cards from collapsing - such as abandonment of the gold standard allowing massive money-printing / currency devaluation and negative interest rate policy.
- Environmental destruction - the continued squandering of natural resources in terms of both raw materials and energy, as well as the rampant destruction of the planet in the name of "profit" sees our environment becoming both more physically hostile and less productive; resulting in increased cost of, competition for / conflict arising from the growing scarcity of natural resources.
- The rise of artificial intelligence - the masses used to be an inconvenient necessity for the privileged few - increasingly this is not the case as AI makes growing numbers of people redundant and essentially unemployable. How do we suppose they're going to react when they can no longer feed themselves? What will be the knock-on effect of their dwindling income on the consumption our capitalist model so desperately relies upon?
- Growing wealth disparity - the system currently in place serves to exploit those with the least to further line the pockets of those with the most. This can only continue for so long until desparation leads to civil unrest and social change; for better or worse. Also, wealth concentration results in lower levels of spending; further cripping economic activity.
- Covid - we have a massively service-centric economy; much of which will be destroyed as people choose to opt out of this non-essential spending; either through fear of infection or dwindling disposible income.
- Brexit - we are a largely consumptive nation that produces little and relies on imports for much of what we consume - food, energy, goods... and we've now voted to effectively destroy the relationship with our close neighbours that facilitates said imports. This will likely result in rising costs of living as well as reduced currency value against those of more productive nations.
I can't see why anyone capable of critical, rational thought can't be concerned about the future tbh, given the current situation.