It has failed as a payment system, as a currency, as a reserve currency, a remittance channel, a timestamping service, a settlement layer, a bank for the "unbanked", a cypherpunk liberator, a money laundering tool, a drugs-by-mail tool, a unit of accounting, a store of value, and as a "disruptive" fintech technology.
When I think of crypto/Bitcoin, I am reminded of Warren Buffett's view on gold:
> Today the world’s gold stock is about 170,000 metric tons. If all of this gold were melded together, it would form a cube of about 68 feet per side. (Picture it fitting comfortably within a baseball infield.) At $1,750 per ounce – gold’s price as I write this – its value would be $9.6 trillion. Call this cube pile A.
> Let’s now create a pile B costing an equal amount. For that, we could buy all U.S. cropland (400 million acres with output of about $200 billion annually), plus 16 Exxon Mobils (the world’s most profitable company, one earning more than $40 billion annually). After these purchases, we would have about $1 trillion left over for walking-around money (no sense feeling strapped after this buying binge). Can you imagine an investor with $9.6 trillion selecting pile A over pile B?
[…]
> A century from now the 400 million acres of farmland will have produced staggering amounts of corn, wheat, cotton, and other crops – and will continue to produce that valuable bounty, whatever the currency may be. Exxon Mobil will probably have delivered trillions of dollars in dividends to its owners and will also hold assets worth many more trillions (and, remember, you get 16 Exxons). The 170,000 tons of gold will be unchanged in size and still incapable of producing anything. You can fondle the cube, but it will not respond.
* https://www.berkshirehathaway.com/letters/2011ltr.pdf
Perhaps it's just the current implementations of 'crypto' that are lacking, and a Crypto 4.0 will get the details right at some point in the future so that it because useful.