https://en.wikipedia.org/wiki/Golden_plates

https://en.wikipedia.org/wiki/M-DISC#History

Basically your media only needs to outlive your drives, retrieval mechanisms, software interfaces, and drivers. Or more properly, your backups need to outlive your live system and the need to restore any data from them. Certainly, data may be more precious than a live system, but you also need to concern yourself with format transfers, in terms of software file formats, filesystem formats, and media design/format.

This is not a difficult achievement. The people marketing long-term archival storage media are capitalizing on ignorance of people who have worked with books and photographs, which are "readable" by human senses. Books and photographs are media which can be preserved and fundamentally produced on archival media from the get-go.

Backup media, since it is necessary to have machines read and interpret them, are an entirely different beast, subject to an entire chain of things to preserve. As I've commented before regarding BD-RE XL, my media and the Blu-Ray drive itself outlasted the system it was backing up, and therefore did their job, without any investment or wasting money on M-DISC "Engraved in Stone Tablets" for the gentiles.