Most people are bad at converting their beliefs to numerical probabilities, are bad at estimating low probabilities in general, and will pick numbers in a certain range that sound low enough even when the number that is actually consistent with their beliefs is much lower. It's like vegetarians who say "well, maybe chickens are sentient enough that they have 1% of the moral value of humans". Almost nobody who asserts that would then save 101 chickens in preference to 1 human.