I think the general demographic thesis on human population peaking relatively soon is that it comes from people voluntarily having fewer kids as conditions improve a la the demographic transition model. There’s no expectation that we hit earths carrying capacity
Oftentimes, what's good for the empire isn't good for the citizens of the empire. So yeah, I'm happy to leave behind the wreckages of a dead empire if it means more for the people in that empire.
Unfortunately, I'm guessing that we'll get the war, or the pandemic, or both. That's how things have historically ended.