I don't understand how this could be true. The chances of you coming into existence require an astronomical number of things to happen in an exact time and order. Changing any number of those variables will cause a chain reaction that will make your existence not happen.

If we assume the universe is deterministic, then changing any of the starting variables of the universe will cause a different course of events playing out. If the speed of light were different, for example, a different course of events would have played out and you and I would have never come into existence.

If we assume the universe is not deterministic, then even if we had another universe with the exact same starting variables, the chances that things would play out exactly the same are also absurdly small.

Just because a set of things is infinite does not mean that it will contain everything. I could have an infinite set of odd numbers, and none of those numbers will be even. It strikes me that infinite number of universes would be the same.