I have similar answers to the question. For me it's a combination of knowing that in the West, no matter how hard you try, another person just living life here will disproportionately contribute to climate change and waste purely because of how society is set up. Sure a revolution would fix that eventually, but having kids is not an important enough desire for me to roll the dice there.

And second, knowing how bad things are likely to get in the near term seems like having a kid is really setting them up for a ton of difficulty and dread unless you're very wealthy.

For me personally, I think communism will come from outside the west and anyone here who can organize is doing it primarily as harm reduction for their community and attempting to slow down how much the west can fuck up for the rest of the world. Having a kid might add another to that group, but it's also part of the two points on climate and doesn't seem fair to the kid or the world to me.

I'm sure others are more optimistic or have a stronger desire that make it worth it to them, and I'm glad for it. Otherwise things would be pretty grim for the left here