Consider the possibility of super longevity, i.e. living as long as possible. Think of it as more healthy years rather than more “old” years.
A simplistic and rather typical view of population growth is that more people means less food per person. But population and food supply do not have a simple linear relationship if the relationship is viewed over time. We are creative minds who work together to improve our condition, so more people can very well mean more food. Other arguments against longevity range from, “It’s up to God when I die”, to “I’d get bored if I lived so long”, to “Being ‘old’ for so long would be horrible”, to the most popular fear of overpopulation.
Longevity does not mathematically effect population. The amount of offspring per couple is what affects population. The poor tend to have more offspring for various practical reasons, so longevity is best viewed as an economic issue. Healthy societies that are better off economically tend to have less offspring per couple, and therefore their population growth might taper off and even decline over time. Healthy economies tend to attract large influxes of immigrants, but can better handle large populations in general.
Think of how many more healthy years we experience now with our current average lifespan of 80 years than we did when 25 years was the average lifespan. Longevity allows more time to gain experience and wisdom and to connect with following generations to properly pass along lessons learned. Ultimately some will choose to make another giant leap for humankind and permanently migrate outside of the Earth-Moon system. Long lives will suit us better for the exceedingly long journeys that we will want to take.
As little conscious chunks of the universe, with an ever expanding curiosity, we will need long and healthy lifespans as we chip away at our knowledge gaps as we get to know our “God”, the Cosmos.