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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 
even just in terms of hardware, find me a computer, hell, find me a CAR, a much more durable machine, that can last as long as a human can without replacement parts. based off of first page google results, the avarage lifespan of a human is about 76 years in the USA, while the average lifespan of a car is 12 years, and the average lifespan of a computer is between three and eight years. and to prolong the lifespan of those cars and computers, it requires specially manufactured artificial parts made of difficult to acquire materials, while a human can just stick seeds into the dirt and pour water and shit on it every so often and as long as nothing goes wrong, there will be regenerating human food in the area eventually. sometimes humans can just find food in the wild and eat it there unprocessed, find any machine that does that. Lifespan isn't everything but it can be an advantage, especially when humans are so relatively low-maintenance in terms of production and resource requirements.
It doesn't make financial sense to manufacturer a car or computer that lasts 70 years because of rapid technological progress. There are some 50s cars still driving around, but they're cool toys. Worse gas mileage, worse emissions, worse handling, no airbags or ABS, etc - for all the practical uses of a car, modern stuff is better. Same for computers, try browsing Hexbear on a UNIVAC.
Replacement parts are an engineering choice. Over the design life of the system, usually it's cheaper to say "swap these relays every 10 years" than to put in a huge durable relay that will probably last for 75. You'll find some elevator computers and other industrial controllers with long lifespans, but pretty much the only systems you will find no replacement parts are things like the Voyager probes.