Seems to be a recurring theme for you this last few months. Don't know if you have a particularly grim view of the future or something and while mine is not the rosiest we are not going to see a collapse, and if we do then we are fucked anyway.
Best depends upon risk you are willing to take. If "chances are I won't lose it all but if I did then I could start over and work a bit" is the risk vs "50% of the population are in this fund and will not be able to retire if this goes pop, if growth beats inflation though then all good", and in the case of gold you are content to leave it in your floorboards or whatever and have nobody know what goes should you deem it necessary to cash in then yeah you can play with some of the more creative instruments, or have a "would suck but can afford to lose" amount invested in them to play with.
I should note though that gold is not the only precious metal
https://www.gold.co.uk/gold-price/5-year-gold-price/
https://www.gold.co.uk/silver-price/5-year-silver-price/
Fiat itself. Will depend upon the stability of the countries in question. I doubt any are in a hurry to abandon theirs (give or take joining a greater block) and will probably remain viable for both paying taxes and day to day uses (even if the mechanism might change -- whether we will see mobile phones meaning everybody including the dude selling me a hot dog takes payment from those a la China any time too soon I don't know). I don't imagine any of those listed are going to go failed state a la Venezuela or South Africa any time soon. China might struggle and Japan's debt crisis could get quite fun, the others could also not represent the best store of wealth if growing it to have an easy life is your plan.
That said most of the west has enough people, enough legacy skill and whatever else that even if the "decolonialise STEM" folks have their wildest fantasies come true (it won't and basic economics will see to that -- the bridge that stands up and does not rely upon witchdoctors to bless the wind away tending to be the one opted for, even if the witch doctor might con a few people a couple of times, and already we are seeing a bit of a shift to self education and online delivery from non traditional means anyway), along with China's colonial ambitions coming true, that things can bounce back where various parts of Africa and South America are well and truly fucked by dint of no great legacy education/industrial capacity*, being a thrall of China or the world bank, and most of their best and brightest that do win the genetic lottery wandering off. To that end keeping your monies split between a few western states will probably see you able to get by at least.
Some will probably get a bit more authoritarian (as it stands cash is almost a dirty word in a lot of places and not a trivial thing to use -- you might be a money launderer, tax evade or a drug dealer, to say nothing of civil asset forfeiture in the US which... one does not turn off a gravy train like that without serious resistance) and might get a bit tax happy.
*for them and for "the west" I am curious to see what will happen when more localised industrial capacity becomes a thing by dint of CNC machines and product runs using them getting to be really good. First to adopt, first to adopt well and one to delay so as to deploy all gen 3 where others are using legacy crap all being things to watch for that one.
Short version. Keep it if you want, diversify your assets a bit.
Might as well do politics section so song
