From the communist manifesto:
Freeman and slave, patrician and plebeian, lord and serf, guild-master and journeyman, in a word, oppressor and oppressed, stood in constant opposition to one another, carried on an uninterrupted, now hidden, now open fight, a fight that each time ended, either in a revolutionary reconstitution of society at large, or in the common ruin of the contending classes.
Does common ruin mean a miserable outcome where the oppressed classes 'lose' against their oppressors? Or is it a situation where all classes suffer? Or does it mean something else?
Capitalism can't continue, it's internal contradictions cause the rate of profit to fall even as they squeeze the last surplus value from their workers, which in turn causes the rate of profit to fall until all you have subsistence workers fuelling an economy that only produces goods for the idle upper class.
At this point for various reasons the system jams, they can't innovate because they've sucked all surplus value from innovative labour, they can't grow because labour is at maximum exploitation, which means there's no profit, and they're idle so they receive no income from labour.
So the poor have no income, the rich have no income, and the system collapses as the rich starve like the poor in their mansions, surrounded by the ossified corpse of their possessions.
But with no organised workers, a new system isn't ready to step in. so the whole thing just catastrophically degrades like the Bronze Age collapse. Eventually a new system will develop, but most of the population dies.
Now add climate change to that and realise non-industrial societies can't survive 4C of warming.
Thank you for the explanation.