I think it's a desire for some kind of closure and a grand comeuppance. There is some hope-infested idea of justice: the evil will die, the good will live forever.
People actually throw money at these creepy prophets of doom. Thinking what? Doom insurance? Somehow they will get a good table up in Heaven?
Life kind of rolls out like a long, very confusing movie. Lots and lots of actors, lots and lots of plots, lots of conflicting stories - good people struggle, bad people thrive.
And we've joined the movie in the middle, lots of stuff has happened before we entered the theater, and lots of stuff will happen after we exit.
And we are at most bit-players. Of course we star in our own little dramas, but our dramas are barely a whisper of a drop in the big ocean of experience. It's sometimes all too humbling.
So we imagine grand conflagrations! We imagine a Big Daddy up in the sky who is gonna sort it all out for us. We imagine lots of silly things. And stake our lives on them.