Interestingly the people who say others should die to “fix” overpopulation change their minds when they’re up. We can solve overpopulation in other ways than letting people die.
It's obviously bad to want other people to die but there is a case to be made that no life (that can suffer) should be created. It also depend on what we mean by immortal, are they technically just alive? Or actively flourishing?
Sustainability would become vastly more important than our current short term horizons.