throwrugtime
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.)