“How many children are you and your wife going to kill, to get the one you want?”
Even in the course of natural sex, more fertilized eggs die than go to birth. How many fertilized eggs died to get the ones you wanted?
Irrelevant. With natural sex you aren’t in control of or responsible for the process of implantation. Your responsibility starts when you are successful.
With IVF you are taking charge of it. I know IVF couples who claim their failures as lost children and the numbers are pretty shocking to me. There is no way I would be willing to go through that process.