Crypto
Property
Gold
Diamonds
Cash will lose value with inflation
Most cryptos, i.e.
altcoins can be flushed down toilet as a store of value.
Bitcoin may still have a great future (let's at least wait until autumn 2020 before declaring it dead), but bitcoin's present sucks.
Property in most parts of the World is not a good store of value. Even in the West, properties are burdened by taxes, shoddy construction, repair costs, risk of the neighborhood turning into a s-hole etc. etc.
Diamonds are illiquid and require special expertise to price reliably, so they mostly lose value right after you walk out of store. Tens of percentages, I assume. Diamonds are not that rare and they have good substitutes, such as moissanite and zirconia. An average person can't tell these apart.
Gold is a way to store value. Sometimes good, sometimes not good, mostly just mediocre. Gold has the best stock-to-flow value right now (about 62), but it will be
surpassed by bitcoin in the next decade (if bitcoin survives that far).
I guess competition / market forces guarantee there is no store of value people could rely on at all times. All items on that list - even cash - work some of the time, but not all the time.