> A bias for optimum brain, liver, and lung capacity/health seems like the rational choice. So why do so many forgo that?
If you want to maximize long-run happiness over the course of your lifespan, it's not entirely obvious that the rational choice is to abstain from drugs and alcohol. Many drugs cause little to no impairment to long-term cognitive function, especially when used in moderation. And according to the people that use them, some drugs have admittedly great benefits, ranging from spiritual enlightenment to making music sound better and food taste better to simply broadening one's perspective.
If you want to maximize long-run happiness over the course of your lifespan, it's not entirely obvious that the rational choice is to abstain from drugs and alcohol. Many drugs cause little to no impairment to long-term cognitive function, especially when used in moderation. And according to the people that use them, some drugs have admittedly great benefits, ranging from spiritual enlightenment to making music sound better and food taste better to simply broadening one's perspective.