Where do we draw the line between crazy and not crazy though?
End times = Crazy. You must be off your rocker!
Coming back from the dead after 3 days = Not crazy
Virgin birth = Not crazy
Magically turning water into wine = Not crazy
There is something, perhaps, about changing the frame of reference from the past to the future that allows people to more freely patronise those whose characterisation is dwelling in imagination.
It is generally not the concept of the end times itself that gets mocked, but the crazy circumstances he attaches to it like designating various politicians as the Antichrist and setting specific time frames for when it is going to happen.