You argued that on one hand we could save individuals with cancer, and on the other we could save all of humanity. Only that doesn't include the individual with cancer, or anybody else on Earth! I knew exactly what you meant which is that a non-zero number of humans would be alive, but to me that doesn't live up to the grandiose idea of saving humanity.

I don't want to divert money from cancer and presumably other medical research as well, so that the last N humans can live in a space capsule. Mortality rates for cancer have been on the decline for decades, so the issue is not theoretical.