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The irreversible global catastrophe is imperialist militaries massacring people with little risk to themselves. 
The irreversible global catastrophe is assembly line robots at the Toyota plant becoming sentient and going on a freaking epic terminator style mass shooting and enslave everyone except me 
ai will kill us by wasting a colossal amount of time and killing the imagination of a generation. Or it gets owned but we still go down with it because the economy is tied to ai succeeding. Classic crapitalism lose lose