People already have to live with their decisions - and humanity as a collective sucks at looking towards the future at the cost of the now. Living longer won't magically change that.
Well that's an.. interesting take
English-speaking culture is steeped in Christianity (even modern 'wokeism' is just another, more radical iteration of calvinism), and Christianity is a doomsday cult; we're fascinated by doomsday narratives, the end of the world, mass death- we're in love with these stories; look at zombie movies etc. The overpopulation meme is certainly going to be partially fed by how appealing 'the end of days' is to the western mind.
(Right wingers have a doomsday narrative, too, it's just a biosocial one rather than an ecological/geographic one; modern technology and the resulting societal shifts lead to selection against intelligence, and societal decay propagates irreversibly, leading to a future of stupid, lazy, and most importantly small-souled bugmen.)
The people that I do see promoting this sort of population limit theory are new age hippies, vegans and the like. Recently seems very popular with more college educated folk. 'How can you think about having kids when you know how bad it is for the environment'
No. Living longer means we have to live with our decisions. People who live short lives don't have to live with decisions that fucked the later generation years after they're long dead. The population limit on this planet isn't natural resources, but pollution, followed by heat dissipation because humans are all 100 watts space heaters.
Make the best of every minute you have, and live it as if it were your last.
How about we just live our life as best as we can? Trust me, it's miserable living without hope or wallowing in self pity.