Humanity’s chances of realizing its potential are substantially lower when there are only a few thousand humans around, because the species will remain vulnerable for a considerable time before it fully recovers. The relevant question is not whether the most severe current risks will be as serious in this scenario, because (1) other risks will then be much more pressing and (2) what matters is not the risk survivors of such a catastrophe face at any given time, but the cumulative risk to which the species is exposed until it bounces back.
Humanity’s chances of realizing its potential are substantially lower when there are only a few thousand humans around, because the species will remain vulnerable for a considerable time before it fully recovers. The relevant question is not whether the most severe current risks will be as serious in this scenario, because (1) other risks will then be much more pressing and (2) what matters is not the risk survivors of such a catastrophe face at any given time, but the cumulative risk to which the species is exposed until it bounces back.