Since the real world value of cryptocurrencies are so volatile they are a questionable store of value
It will not be so volatile if it’s primary means of transaction for everyone(obviously not yet). Value of thoose cryptos are just like the values of normal money in different countries.
For example, if you can buy an apple for 10 shitcoins, instead of buying it in USD, then the value is not volatile. The problem arises when the apple is 5 USD and you have to transfer the shitcoin amount which is equal to the exchange rate of 5USD at that time.