Fat's question is retarded. t. professional philosopher.
The toddler has actual existence whereas the embryos have
potential existence.
Douglas Hofstadter wrote about this at length. He was initially curious as to why we swat mosquitoes on a whim without giving it a second thought, and his conclusion was that any being's capacity for thought and reflection runs along a cognitive capability spectrum. The lights are on in our heads -- and,
the more intelligent we are, the more conscious we are. But the mosquito, which has an intellect value somewhere arbitrarily close to zero, has a
very dim bulb -- and one that we have no qualms about snuffing out.
Along those lines, the child is much higher on that spectrum than any collection of embryos. We realize this intuitively, which is why most people would choose to save the child. For the toddler has, among other things, a capacity for fear and suffering that the embryos do not share.
Another word about actual vs. potential existence: The embryo implantation success rate in IVF is about 20%. (
https://pubmed.ncbi.nlm.nih.gov/26777262/) IVF's overall success rate is higher, because multiple embryos are implanted and one or two of them might survive.
So, in the average case, 800 of those embryos are doomed. Of the 1000, only 200 will be born.
However,
there is a very small but non-zero chance that none of the embryos will live. The toddler, however,
is alive in the present. Even if the odds of [no children born from the lot of 1000 embryos] is as low as one in 1^1,000,000, it doesn't matter -- the proper thing to do is to save the life that actually exists in front of you with probability 1.
Another practical consideration lies in the fact that it's relatively easy to produce a fertilized embryo in a medical setting. ("Sir, will you jerk off into this cup again for us, please?") The actual dollar-value economic worth of the child, is higher than a collection of 1000 unactualized embryos.