I think not living is better than growing up neglected with only bullying as love. It’s better to not live than to watch your relatives live real lives while you sit in a corner playing a video game so you’re out of sight. It’s better to not live than to have everyone in your family hate you for being dependent, but also hate you when you ask for help on being independent. It’s just not a life worth living for both parties. The real relatives deserve real lives that doesn’t involve taking care of some burden nobody wants, and the other shouldn’t live as a burden nobody wants. So many unwanted kids are put in group homes where they stagnate more solely because their parents didn’t want to try raising them. Death is better than living in prison for being unwanted.
I would be conflicted about a child with infantile tay-Sachs (there are probably other similar diseases, but I don’t know them). That’s a short, excruciating life, and I would not want to live it. But the idea of someone choosing euthanasia for someone else, even someone under their care, is pretty abhorrent to me. It seems too ripe for abuse, and the right to decide to end your own life should not be transferable. The ending of it can be, but only under circumstances determined by the person (so I could tell my husband that I don’t want to keep going if I can’t recognize my children, for example, and when I reach that point, he could kill me, but he can’t decide what the line is).