It's difficult (but not impossible) to find niches where cryptocurrencies are being used as currencies. They are more often described and used by enthusiasts as securities or investments, so it's this aspect that dominates discussion today.

Outside of criminal activity (including "positive" criminal activity like evading the capital controls of authoritarian regimes), there's not much to recommend cryptocurrency as a currency. Bitcoin maximum throughout is several orders of magnitude too small to support meaningful use, and transaction fees on popular chains are punishingly high. I personally like to use payment instruments that can be clawed back in the case of fraud (like credit cards) for large purchases, so I can't really understand the appeal of an irreversible payment instrument for routine use.