None of these examples explain why only the ultra wealthy would get this.

It makes economic sense to fund and subsidize, just like vaccines.

>We show that a slowdown in aging that increases life expectancy by 1 year is worth US$38 trillion, and by 10 years, US$367 trillion. Ultimately, the more progress that is made in improving how we age, the greater the value of further improvements.
>
>https://www.nature.com/articles/s43587-021-00080-0