Is every second person on this fucking website suicidal? I guess the “lemmings” checks out.
As for me, it would have to be a number of people that, by their sudden absence, manifestly affects the life of people I do know and care about. Like, at least a billion or so if randomly chosen
edit: and that means possibly fewer if not random and more focused on my geographical location. If 100 mio die on my continent alone then the rest is still pretty screwed.