I really enjoyed this, but I think those aren't the odds of me being here. Provided with all of those circumstances with the earth, even if it was a different sperm cell or egg cell, or a different great great great great grandparent, that would still be me, so some circumstances do not affect at all that i am living on the earth. They would just be a slightly different me. If you take a crowd of 10,000 people and randomly pick one of them, there is a 1 in 10,000 chance that any one alone will be picked, but it is 100% that there will be one picked.