To doomsday scenarios like the False Vacuum Decay or that the LHC might create a black hole that destroys the world, I always have the same reaction:
My life experiences so far have shown me that the laws of physics are exceptionally stable.
In other words, if the universe is viewed like a video game for example, then whoever coded it did an absolutely superb job addressing every possible bug, glitch, exception, or exploit. Never once have the laws fundamentally broken down as a system, be that when humanity broke the sound barrier, split the atom, reentered the atmosphere, created antimatter, created microscopic black holes, or formed a Higgs boson. The fabric of reality has never once ripped or unraveled due to a paradox as is so popular in science fiction. So is the False Vacuum Decay scenario possible? Sure, under our current understanding. But I put little faith in ideas that the universe has some fatal flaw in it that could lead to ultimate doom for everyone due to one silly mistake or unfortunate circumstance.