Blockchain is a useful bit of technology. The concept of digital currencies is of value. However, the volatility has always been high, and too high for most consumers.
If you were purchasing goods in terms of bitcoin, since the value of the currency fell by 30% at one point, the price of goods you buy would likely increase by 30%.
Holding a currency that changes in value frequently, rapidly and without notice, is not the type of currency that most people want to hold – unless you wish to engage in risky, speculative trading.