If you're looking for ways to eliminate existential risk, then knowing that humanity is about to kill itself no matter what you do and you're just putting it off a few years instead of a few billion matters. If you're just looking for ways to help individuals, it's pretty irrelevant. I guess it means that what matters is what happens now, instead of the flow through effects after a billion years, but it's still a big effect.

If you're suggesting that the life of the average human isn't worth living, then saving lives might not be a good idea, but there are still ways to help keep the population low.

Besides, if humanity was great at helping itself, then why would we need you? It is precisely the fact that we allow extreme inequality to exist that means that you can make a big difference.