Yes, this is called homelessness.
OK, not all homeless people, or even most, but the survival rate for homelessness is absolutely terrible and few care. ( https://www.crisis.org.uk/media/236799/crisis_homelessness_k... "Homeless people are more likely to die young, with an average age of death of 47 years old and even lower for homeless women at 43")
Similarly with the millions of refugees coming from Syria and Libya, "let them die at sea" is a popular position and "murder them rather than letting them in" is gaining traction.
The pandemic has really opened my eyes to just how OK people are with the mass death of strangers.
That example does not strengthen your case. While not unopposed, there are still lots and lots of pro refugee people and many countries let them in.
Homelessness is a far unsexier issue where you can absolutely say people don’t care enough, but refugees are more of a counterexample.
Westerners, on the other hand, will just stay at home thanks to AC and pretend everything is fine.
Of course GDP won't be a big deal. By the time the worst effects are there the Chinese population will have aged to the point where getting rid of the elderly is better for the GDP than keeping them.
People with more money generally can afford more bullets. I wouldn't rely on them.
"live by the sword, die by the sword"
Suppose there was some event that killed all homeless people - it might not affect GDP much. Should we do let such event happen and conclude it's no big deal?