You can buy gold. Best way to keep them safe is burying them to somewhere you can remember but others can not even think to dig. Like near your favorite tree in the village or next to a rock something like that. It works almost perfect for thousand years.
LOL, very true, but a bit long term on the return.
I have "traditional" investments/retirement savings. In crypto, I'm in everything I can. I mine, dabble in day trading, buy in to what look like possibly GOOD new projects, stake several coins, etc...
As in any portfolio, diversification is critical.