Just to give an idea of the unlikelihood we’re talking about here, you can model this as a Bernoulli process with a binomial distribution.

If N is the number of beings potentially snapped, then (√N)/2 is the standard deviation. (If you’re curious about why, you can read more here.) So for a 8.2 billion people, the standard deviation is ~90,000. The chance of being less than ~3 standard deviations is 0.1%. That means there’s only a 0.1% chance of snapping less than 4,099,720,200 people.