Now, not everybody's in it for those reasons. But there are quite a few very vocal christians who really want the end times to come, and, having read a (there were several) revelation/apocalypse, know what has to happen first. If you've got a dependency issue, you resolve it. Gotta have the Temple rebuilt before God comes back? Best get cracking on getting it built, right?
I wonder if it occurs to the Jews that they're being used. Sure, some of 'em might make it to Heaven ... but a lot won't according to the rules as I understand them. They'll happily ignore the one true messiah they've been waiting for, get the help of those who didn't, and kindly participate in bringing about their own doom (according to one point of view, that is.) Now, maybe they realize this, and believing their benefactors to be heretics, just gladly take the help without worrying about the consequences that won't come about.
But why the hell (oops) are (some) christians obsessed with bringing about the end of the world as we know it? Shouldn't they want more time? Shouldn't they be begging God not to drop by for a visit anytime soon? Shouldn't their entire focus be on doing their utmost to convert as many people as possible before the end, possibly delaying the end as long as possible? Self-interest? When you die ... do you get bored waiting for the end to come? Is that it? Do they fear roaming about as a ghost once they die? Are they afraid to die and just -really- want the whole abduction (rapture) thing to happen? Heaven's all nice and good and beautiful and perfect, but that's not the world you have a chance to change. This is it. Assuming you don't get bored playing ghost for a while, isn't the end of the world just as good (in that respect) whether it comes tomorrow or practically-never?
I guess there's the "stop-loss" idea: if you think we're creating more hell-bound humans than we are heaven-bound, maybe the end of the world can at least stop the flow of souls to hell (by simply not creating more souls, by not having time to do so.) That sort of clashes with the whole "populating the earth" idea, but ... oh well: that was the old covenant.
Shouldn't you be out trying to save people? Why are you still reading this? Shouldn't you be freaking out about the whole "thief in the night" idea? (By the way ... most people don't go to great lengths to prepare themselves so an unexpected guest, like a thief, will have an easier time coming. It just rarely makes sense.)
I just don't get it. (Obvious, is it? Thanks. Shut up.)