What do you do when you’re so rich you could live to be a hundred and still not spend a noticeable fraction of your fortune? Buy yourself some more time. Literally.

The Amazon founder Jeff Bezos, 57 was reported last week to be among the backers of a new “rejuvenation company”, Altos Labs, a Silicon Valley start-up that has set its sights on understanding why we age and how we might prevent it — and ultimately work out how we might live for ever.

Bezos is not the only billionaire looking towards his end days. The men behind Google and Facebook are also dabbling in the dark art of manipulating mortality. But are they altruistically investing for the good of humanity — or is this.