I think pinning a probability number on this (outside of context of being forced to gamble or otherwise forced into making a decision dependent on probability of this) is simply innumerate. Suppose you attach a number to it. Then there's a situation where it is too high (Pascal's wager) and possible situations where it is too low (we discover that incredibly simple laws, simpler than laws of physics, lead to emergence of singleton intelligence that proceeds to simulate universes with life, and then you start rejecting Occam's razor because you were too atheist)