How to keep them safe,
This is a complex question that requires an answer specific to each case.but also how to pass them on to heirs or friends (so that they know what to do with them?).
It's obvious: instruct on the actions that need to be taken in the event of your departure. For example, in the form of a classic envelope with a Informing others while preserving your own security can be a real challenge in some countries.
And then there's betrayal, divorce etc...
Therefore, in parallel with financial capital, it is necessary to accumulate social capital. That is, surround yourself with people you can trust. But the main rule: don't trust anyone. And then there's betrayal, divorce etc...
Therefore, scatter parts of seed phrase all over the world, so that in case of divorce your ex can't get sole access to your wallet. What are the solutions?
The decisions of some may be directly harmful to others. Should not blindly follow other people's cases.