Longtermism relies on the theory that humans have evolved fairly recently, and thus we can expect our species to grow long into the future. The world’s current population is really a blip; if all goes well, a huge number of humans will come after us. Thus, if we’re reasoning rationally and impartially (as EAs pride themselves on doing), we should tilt heavily toward paying attention to this larger future population’s concerns — not the concerns of people living right now.

https://www.washingtonpost.com/opinions/2022/09/05/longtermism-philanthropy-altruism-risks/