Crypto coins are functionally the same as equities in that they have a constrained supply, reward early participants, are used mainly to raise capital in the form of an external currency, with the exception that in comparison to owning equity, owning coins represents no proportionate value of any underlying value in particular.
Because their money supplies are constrained, volatility relative to other currencies, in addition to transaction fees and major security and privacy flaws, make them worthless to transact with. You wouldn’t buy pizza if it takes you 5% in fees, 4 hours for the transaction to process, and your wallet value might increase or decrease 50% in that time it takes to process the transaction.
Transaction fees, transaction times, energy expenses, and locked wallets are technical challenges that can be overcome. But the money supply issue is at the heart of why cryptocoins can’t be a transactable currency. A fixed, inelastic money supply cripples the ability for ordinary, non investing participants in an economy to acquire and use it. Bitcoin neither represents any underlying wealth, nor makes it possible for people in a marketplace to transact with it.