We don't really need LLMs like we don't really need the internet. We don't really need that blog, nor do we really need Netflix, porn or Facebook.
Individuals value things differently, so attempting to do society-wide prioritization is always going to be a reductive exercise.
For example: Your local cafe doesn't need to exist at all. You could still drink coffee, you'd just have to make it yourself. That cafe is taking up space, running expensive commercial equipment, keeping things warm even when there aren't customers ordering, keeping food items cool that aren't going to be eaten, using harsh commercial chemicals for regular sanitization, possibly inefficient cooling or heating due to heavy traffic going in and out the door, so on and so forth.
Imagine the environmental impact of turning all cafes into housing and nobody driving to go get a coffee.
Again, this just feels like throwing your hands up in the air and saying "it's too hard to decide!" But we have to take decisions somehow if we're going to do anything.
Yes, that's the challenge of centralizing economies. You aren't going to be able to do so efficiently because you don't have every person's preferences.
If by "we're going to do anything" you mean presumably fiat power to ban LLMs, then you're better off using that fiat power to just put a sin tax on carbon emissions and letting people decide where they want to cut back.
Take one fewer hot shower a week and you've saved enough energy to power a lot of ChatGPT queries. Play one fewer hour of Minecraft. Turn off raytracing. Eat one fewer burger per month. All of those things would save more energy than forgoing a few ChatGPT conversations.
Individuals value things differently, so attempting to do society-wide prioritization is always going to be a reductive exercise.
For example: Your local cafe doesn't need to exist at all. You could still drink coffee, you'd just have to make it yourself. That cafe is taking up space, running expensive commercial equipment, keeping things warm even when there aren't customers ordering, keeping food items cool that aren't going to be eaten, using harsh commercial chemicals for regular sanitization, possibly inefficient cooling or heating due to heavy traffic going in and out the door, so on and so forth.
Imagine the environmental impact of turning all cafes into housing and nobody driving to go get a coffee.