Say there were effective therapies that could lead to indefinite lifespans (not just healthy aging). Would everybody be willing, interested or able to use them? I don’t mean just a few dedicated people like here at Longecity/Imminst, or a few health enthusiasts. I am talking about every human on Earth.
You ask:Would everybody be willing, interested or able to use them?
This is actually three questions, but initially the answer to all (interested, willing, able) is no.
As in any watershed moment in human development the transition is generational not instantaneous. There will continue to be injustice and denial for reason of society and economics. There will be self denial due to culture and ignorance, but above all there will evolve free choice. That choice will become eventually a right of the individual but it is naive to expect it to start out that way.
From one point of view, even in the 21st century people are still dying from hunger, lack of water or lack of basic medical facilities. How can these people ever be in a position to use life-extension technologies?
This is a separate issue from longevity technology specifically but a question of society, economics and culture that is all pervading. It is overcome one day at a time and by one person at a time multiplied by billions. Just as it is being overcome across the world right now with the demands for food and democratic rights of expression and representation.
Once this technology is conceived of and recognized as possible, eventually it will be achieved. Once achieved the next phase of creating free choice and the right of access becomes the next struggle. Just as economic justice is the rising struggle of our current era.
From the other point of view, who would have predicted that mobile phones and internet will be used so widely, including by villagers or farmers from very poor developing countries? Maybe, these life-extending technologies would be embraced by all, if and when available.
Actually need, demand, and economic accessibility, are the driving issues in the examples you provide as well. Mongolian yak herders have cell phones because once the technology become economically feasible it provides an economic advantage and it was vastly less expensive an infrastructure to build than assembling a communications grid across vast stretches of empty desert for a nomadic people.
Why is it that people can easily lay their hands on technological devices (digital assistants, laser guided guns, satellite communication) and yet are unable to provide a malaria tablet, or a few clean dressings and syringes to those in need?
These are separate questions because the malaria pills are available yet many deny themselves due to cultural perceptions and mistrust or are denied access by those that take advantage of poverty to manipulate events to their own ends. The medicines and technology to feed people exists but a variety of factors contribute to diminishing access, including the lack of will on the part of those without such need to sacrifice whatsoever to help meets the needs of those who do. Selfishness and the lack of empathy and sympathy are not anymore common among those seeking longevity than they are among the general populace, including in nations both rich and poor.
Digital assistants are not merely a substitute for cheap labor but are only important when their use provides advantage economically. Most of these technologies are not desired by the poor because they are faddish, they are desired to provide some advantage for economic competition.
As for the weapons, so long as there are oppressors and the oppressed there will be demand and those that go without freedom will go without food to find a weapon to fight back with. Violence may be the last resort of the incompetent but it is still an all too effective last resort.
Sorry for the bit of a ramble but I am in a hurry to split wood and make music while the sun shines.