Indeed, one of the stories at qntm features discovering something like the Fountain of Youth, and describes the organizational nightmare of letting a large enough proportion of mankind use it.
Harry Potter, however, if he makes himself immortal, will have a lot of time. Even if a lot of people die of old age or illness before he can reach them, he can still reach a lot of people given enough time. He would also need to figure out some efficient way of space travel and terraforming, otherwise he could cause overpopulation.
Indeed, one of the stories at qntm features discovering something like the Fountain of Youth, and describes the organizational nightmare of letting a large enough proportion of mankind use it.
Harry Potter, however, if he makes himself immortal, will have a lot of time. Even if a lot of people die of old age or illness before he can reach them, he can still reach a lot of people given enough time. He would also need to figure out some efficient way of space travel and terraforming, otherwise he could cause overpopulation.