Um, what?
This isn't about chance and probability. It's about potential. An egg can become a person, but
only if it encounters a sperm cell. Likewise, a sperm cell can become a person, but
only if it encounters an egg. Unless these conditions are fulfilled, this potential is wasted.
The only rolling of dice that could be involved would be to determine whether or not fertilization actually takes place when these two factors meet.
Oh, and to the person who spoke against spilling seed, remember that if a male does not touch, have sex, or otherwise "let it out," the excess buildup of sperm will be released when he urinates.
The only way to avoid this would be to get married and start having sex as soon as soon as the little buggers learn how to swim, which I believe happens at around age 12-14. It would also mean having sex on a very regular basis for the rest of your life, which for most men just isn't feasible. What if you become a widower? Depending on your views about remarrying, you could really be in a LOT of trouble!