There is no coherent reasoning with this crowd. I have had hundreds of discussions of this form. In the end, in every case: it's just rationalized copium about the fact that they will die.

It is very easy for them to say "people should die" on an Internet forum. On their (or a family member's) deathbed, presented with a cure to death, they would say something very different. When push comes to shove, no one but the suicidal actually hold the belief that people should die.

In my experience the pro-death crowd takes this stance because they don't dare to dream of a world in which death is cured - because you can't get hurt by the potential of a future you don't believe in.