What "happens to them" is that their life is sustained by calories and nutrition they would not otherwise be able to afford.
This kind of GMO is literally (not figuratively!) life-saving technology.
Just like the Haber process enabled fertilizer to be produced cheaply, saving billions of lives. Without it, India would have faced mass-starvation and its population would be half of what it is now.
Now, you may wish to argue that the World has become overpopulated as a consequence, but then the question becomes: How would you reduce the population?
Most people would prefer to elevate societies through sufficient sustenance, comprehensive health-care, and stable governments. This seems to reliably result in negative or zero population growth.
Your view seems to be that it's preferable to starve hundreds of millions to death, leaving the survivors in abject poverty to avoid... what... "meddling with nature"?
No, you misidentify me; I'm not one of those anti-human "the world is overpopulated!! Degrowth!!" People. Better food is good; I just assume someone will fuck up at some point while we're figuring out nutrition and genetic engineering.
Let the hundreds of millions eat what they will; any problems or mistakes with gene-edits that lead to poisoning, carcinogens or insidious malnutrition will be sorted out after a few decades, I'm sure. I just don't want to be the guinea pig, if I can let a hundred million other people do so instead!
Those hordes of hungry mouths are a great laboratory: diverse, far enough away and poor enough they can't take revenge on you if you accidentally poison them, etc.
