So you wanna build an aging company

Dude, let's not jump the gun here. If a fear of an entrenched immortal oligarchy is your justification for the idea of forbidding billionaires from funding medical innovations that extend life and health-span, you're being a huge bit too optimistic, to the point of absurdity.

We'll be struggling, failing and incrementally advancing with medical advancements that merely stave off the vast hellscape of age-related and degenerative diseases for a moderately longer healthy life long, long before we discover a way to enable a reality of immortal billionaires.

That aside, even if we did, I have my massive doubts about the inevitability of all you predict. The vast range of technologies already available to billionaires today would make a medieval king or Roman emperor salivate at having them with dreams of total control, yet if anything, the technologies they do have (and which states have), have only increased the complexity and Swiss cheese nature of the modern world in the direction of also expanding basic freedoms and instabilities of power of all kinds for more people than ever, often directly at the cost of former power monopolies.

What's more, right now, both massively wealthy states and huge corporations administer much of what happens in the world, and both could arguably claim to have much more power, resources and even in a certain way near immortality than any hypothetical immortal billioniare oligarch as per your prediction, yet hysterics aside, I don't see either totally killing off democracy at all.

People still protect, governments still change and fall, big companies still go bankrupt or lose market share, and no one power center is nearly as in charge as some paint it to be. If it were, you wouldn't be predicting, you'd be speaking in the present tense perhaps.

Either way, the groundwork of you fear already exists in a fashion, and it's not creating quite the total boogeyman you're trying to depict.

Don't let sci fi guide your perception too much, reality is so much more complex and counterbalanced all over the place.

"It's important that you must die, so that the rich can also die" -- you. Can you really not come up with better solutions to psychopaths having too much power than everyone must die?

One intuition pump that always works well in these discussions is to imagine that death is already solved, and all your worst nightmares are true. So we live in a world where a small number of humans own and control everything forever. What is your proposed solution? Kill everyone who is old? Really? That's the best you got? Literally just force everyone to die?

We already live in a world where most people's lives are made shit by the whims of a few rich psychopaths, it's just that right now the specific set of rich psychopaths randomly changes every so often. So? Why is that better? Why does it matter to me that the boots on my neck belong to Elon Musk and Jeff Bezos instead of John D. Rockefeller and Cornelius Vanderbilt?

Child mortality rates are lower than they have ever been. They are basically zero in the developed world, and falling quickly throughout the developing world already. It's mostly a solved problem. Where it remains high, it's typically a symptom of other problems which prevent people from accessing adequate food and medicine. These circumstances almost always have their unique nuances that prevent them from being simply addressed by a single large effort, instead demanding a unique response informed by experience with the local conditions.

Adding a single healthy year of life to every American who lives to be over 70 would add about twice as many healthy person-years than reducing the US infant mortality rate to zero. Reducing the world infant mortality rate to zero would be equivalent to adding roughly two healthy years to the lifespans of those who make it over 70.

What school of ethics holds that you should oppose medicine to treat yourself so that other people are also denied the benefit?