Whenever someone tells me that they believe the world is going to end on a specific date, or during a specific period of time, I offer them this bet:
I will bet you my house and land against your car. If I'm right, and the world doesn't end, you owe me your car. If I'm wrong, you can have my house and land.
Optimist: pays 20 bucks to pessimist now.
Pessimist: pays 40 bucks to pessimist, if world hasn't ended in 2020.