you are right, this is a problem we already have. we can observe what happens in our society for example concerning the UBI : the old people struggled decades with wagework they don´t really like to make a living. they are the majority of people, who lived their life in a constant, suppressed form of suffering, enduring the slavery and heteronomy every day with the help of the belief, that this way of living is an inevitable stranglehold of life itself with no solution.
yes, and more. it helps much to maintain emotional wellbeing when you convince yourself that you do the right thing with your lifestyle. every employee has to tell himself “i am a good person, because i work hard and do the best” and for some their money is their proof and reward and for others the survival of their familiy. even if their company ruins the lives of so many people, and destroys the environment, they believe, they do a good deed. and this majority of older people really gets furious when they imagine that their children or grandchildren would be much more free with the UBI than they were their whole life! even the thought is painful for them, because it not only proves their believes wrong, it also means that they feel, they suffered for nothing. but there are exceptions from this majority. and it only depends on what they believe and feel. many old people might claim that they want younger generations to live a better life than they lived, but only few mean what they say. those are the exceptions who don´t feel pain and envy and who believe that they suffered for progress and a better life for following generations. but this mindset is only possible for people who kept their suffering and discontent alive ( maybe this is part of your second condition: “subjective imperfection”) without numbing it with what you call “brainwash”–> “i am a good person, because i work hard , i do a good deed..etc..”.
but there are more psychological ways to block progress. if you learn one way to do things, it could also be painful to be told, that there is a very much easier method to achieve the same goal, or that your work is not needed anymore because machines could do your job much better. the majority of people feels useless, the exceptional people feel relieved. but they are the ones who always believe that there is more to life than their job and they learned much more than the mere skills, their job required. people, who only possess abilities for one job will be devastated to be replaced, because now they are old and without competence and they could not teach anybody their abilities because the technological development turned the situation into something “perverse”( from their perspective): if those old people want to contribute to the world again, they will have to be the pupils again and the young will be their teachers! many old people can not stand a situation like that because then they would feel much more insufficient than they ever felt in life since they were children.
no matter if we talk about a society with indefinite lifespans or our current society, everbody is in danger to develop a mindset that could block progress. and it is not only the problem of old mindsets of people in power, it suffices if they are the majority.
what would we feel, if future generations would abandon schools and universities and books because they could learn everything that way in the movie “matrix” neo learns martial arts, so they learn in minutes what once needed years and within hours, that took a lifetime to learn…wouldn´t we envy them ? what, if they abandon grades and competition and only focus on to learn what is the most fun to learn and also do, what is the most fun to do? wouldn´t we have the feeling that they destroy our culture and our heritage and that there must be something wrong with this lifestyle? wouldn´t we be relieved if they found out that our style to learn things had some “pros” (for example was more profound) .. and thankful, when they decide, not to demolish every univerity and keep some libraries?
but with all my deliberations i probably only scatched the surface of your first condition for progress: