Spot on description of what crypto currencies are. They are just "assets" with no meaningful real value. We only see their prices explode because we see prices in all asset markets explode. That is not a success story of crypto currencies, it's an asset bubble caused by poor macroeconomic policies. The low-interest-rate of the recent years has brought us there.
And why are interest rates so low? Because politicians and economists (mostly neoclassical) incorrectly assumed that monetary policy by central banks can control consumer price inflation by indirectly controlling money creation through lending of private banks. But they evidently can't because the amount of money does not cause such inflation. Rising salary does. More money in the wrong place just causes asset bubbles.
But since at least a decade (in japan even since about 25 years) companies do not lend money anymore even with zero interest rates. Central banks can lower interest rates but they can't force companies to invest. This is perfectly described by economist Richard Koo.
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Instead money goes into assets. But if one saves money there must be another one that takes the same amount as debt. Currently it's the state.
Crypto currencies are not the solution, they are a symptom of poor monetary policy. Private banks are creating billions of additional money every year through lending. But those credits that have in the past been used by companies to invest into an increase of productivity increasingly flow into the pockets of the already wealthy that instead use it to bet on rising prices of assets, no matter if it is stocks, real estate or crypto currencies. The whole development reminds me of what happened in 1929.
Currencies that are unregulated and subject to massive speculation on the market will never be accepted as general means of payment because they are inherently unstable and they lack an authority that enforces demand for it through taxation.