One problem in determining the likelihood of you ever existing — given only one finite lifetime possible, and an infinity of potential selves — is TIME

If time is infinite, the likelihood of you EVER existing – given that you can only have one finite life at most – must equal infinity over infinity…

But according to Stephen Hawking, time actually began at the Big Bang

Even so, time itself might still be infinite (it may never end) – and, the likelihood of you ever existing still equals infinity over infinity…

If time does begin and end, your likelihood of ever existing becomes some whole number (number of selves that do get to exist) over infinity …

The likelihood of you existing right now, given an infinity of possible selves, is still unknowable, but even smaller than the likelihood of you existing right now if your existence depended upon the sperm cell/ovum combination…