You’re not thinking deep enough. Real trade (across time and cultures) has always been based on utility. Would you rather wake up and put food on the fire, wrap yourself in warm clothes and snuggle with the family, keep the rain off your heads, tend your crops, and be able to shoot the bastard that wants to take that from you... or would you rather rub a gold bar? Gold has no value because it has no utility. Therefore it is fiat.
Gold can be declared to be official money, or at least it has in the past, tho the value, for whatever reason, can’t really be undeclared, so to speak. Heck, it can’t even be destroyed! Notes and bonds can be reneged upon. Money represents a claim on future goods and services, and so the things you mention - a roof over one’s head, hearth, and home,
are very real necessities and are why people save money to begin with, of course.
I can’t spend my savings bonds at the hardware store. I don’t fondle my 401(k) statements, same principle. I like cash, we own stocks and bonds, it’s just those long time horizons that always left me a bit skeptical. If it works out in 30 years, great. Excellent. Except, what if it doesn’?t Then what? Start looking for a new career at 65 or 75? See where I’m goin’ with that?