I've discussed what happened on Sept 11 2001 with some jws. I asked them: 'how did you feel when you saw 3,000 of your fellow US citizens die like that? Now imagine billions of people dying in a similar manner - buildings crumbling and so forth. Is that really what you want to see? Do you really understand what you are hoping and praying for?'
As pointed out above by the poster who nicely quoted Amos 5:18, do they really realize what they're asking for?