The other thing is if I get hit by a bus and no one can work out how to decrypt a backup or whatever.
Documentation, documentation, documentation. No matter what system you have, make sure your loved ones have a detailed, image-heavy, easy to follow guide on how restorations work - at the file level, at the VM level, at whatever level you are using.
That being said, DVDs actually have quite a short shelf life, all things considered. I’d be more inclined to use a pair of archival strength USB NVME drive, updated and tested routinely(quarterly, yearly, whatever makes sense). Or even an LTO tape, if you want to purchase the drive and some tapes.
You can put your backups in something like VeraCrypt. Set an insanely long password, encoded in a QR code, printed on paper. Store it in the same secured location you store your USB drives (or elsewhere, if you have a security posture).
You may also consider, if money is not a concern, a cloud VPS or other online file storage, similarly encrypted. This can provide an easy URL to access for the less tech-savvy, along with secured credentials for recovery efforts. Depending on what your successors might need to access, this could be a very straightforward way to log into a website and download what they need in an emergency.
If you buy your LTO drive new, then yes they rip you a new one, for sure! Buy it used…but it still will cost you a few hundred. Like I said, if money is not a concern. If losing the encryption key is a concern, then USB is still your best bet. Make two, keep them simple and unencrypted, stick em in two different safes, update them regularly. And print the documentation with pictures!