Historically, every currency has failed. All of them. Some are pretty old but all of them have at some point failed. There is no currency that's been around since the beginning of civilization or recorded history that's still here. Just cuz in Russia it fails like every 10 years

and in the US it hasn't for 250-ish doesn't mean anyone's got some magic currency that lasts forever.
People can pile on gold but it has little actual use besides luxury so that's stupid in case of worldwide economic problems much more severe than right now and/or zombie apocalypse.
You can buy industrial commodities like metals and earth magnets and general raw materials but in the case of nuclear war or virus apocalypse, those are almost as pointless as gold.
You can invest in weaponry but that degrades.
You can buy food, air, and water but those degrade.
So really, you're screwed no matter what....unless you invest in learning electrical systems, engineering, and survival skills. Those are universally valuable in all circumstances between today and a nuclear zombie economic apocalypse virus war

But anyway, BTC is extremely likely to not get destroyed or go away as a whole so it's a pretty respectable investment at the moment.