True, but advanced technologies tend to quickly become cheap enough for everyone to buy - just look at cars, computers and mobile phones in the last century. Sure, not everyone has access to items of the same quality - I tote around a cheap Samsung brick while everyone else has smartphones - but if it's something as easily reproduced as a pill then even this wouldn't be a problem.

A similar concern as the one you write about has been raised with regard to nootropics (cognitive enhancement medications) - that they'll be available only to the wealthy elite, further entrenching their financial superiority. But actually, nootropics are of more benefit to an individual the more people who have them. I'm better off if everyone has nootropics than if only I do. Perhaps the case is similar with regard to immortality drugs.

One of my largest concerns is that it is pharmaceutical companies like GlaxoSmithKline who are trying to produce these pills; I imagine they'll sell them at several thousand % profit over the production cost.