[jonmrodriguez]

I think most billionaires are not scientists and don't realize that life extension is any more possible than magic.

Once some steps toward life extension start happening without billionaire's help, and start to become part of popular culture, then billionaires will realize it's a thing.

Also, inertia. You probably strive to live a similar lifestyle as your parents and your friends, rather than (for example) selling your possessions and spending your life backpacking the world, even if the latter might rationally be a better option if it occured to you.