I'm not fear-mongering; I'm just a pessimist. My scenarios are “unbelievably unrealistic” and “apocalyptic sci-fi”, respectively, but I wanted to make sure I got an upper bound on the worst-case. I don't know much about the topic, so I had to go into “I know this is unrealistic” territory for that.
See also: https://xkcd.com/2261/ and https://xkcd.com/883/.
Not sure I agree with their ‘hundreds of millions (per year)’ figure. That seems like unnecessary fear-mongering. But maybe ‘hundreds of thousands’ or ‘millions’, which is still not great.