If you sent 1 million sats to a Bitcoin wallet and buried the keys
In 100 years, you dig it up
You still have 1 million sats
Exactly 1 million sats - no leaks
Bitcoin is not an investment
It's a battery 
Discussion
Funny you should say that.
I have two sets of keys engraved onto 2 separate 308 stainless steel plates buried in my garden.
Definitely don't tell people that IRL and hope your nym never leaks.
And depending on the fiat quoted price of Bitcoin, you may just have given your relatives a financially sound life.