I've always wondered if this (kinda widespread?) theory stems from most people thinking that "infitnity" includes every possible option, which is not true.
(I'm a layman, too)
(I'm a layman, too)
Mathematically, "infinity" doesn't imply every possible option. But in terms of quantum physics, yes it kind of does include every possible option. There is a kind of joke classroom exercise in quantum physics class to calculate the probability that a piano would instantaneously rematerialize a meter away from its previously observed location. Its 10^-[ ridiculous number] but still thats not zero.
The size of physical reconfiguration of a person's brain to cause them to break out singing is a much smaller deviation so comparatively likely. So 10^-[somewhat less ridiculous nunber]
So tiny probabilities become essentially guarantees unless the heat death of the universe is so thorough as to erase the slight probability that the whole thing pops back into existence.
(But I just looked that up too because this concept is mostly used/assumes in statistical physics)
(Still a layman, though.)