Or fiat currency, simply. Cryptocurrencies are mostly used as an investment, and if you have an investment, which you therefore expect to be worth more in the future, and a fiat currency, which you know depreciates, which one are you going to spend to pay for a coffee? Leaving aside the scalability problems that in a hypothetical future in which everyone would want to pay for coffees with Bitcoin there would be, since the channels have to be opened in the main chain.

And stablecoins have come to be used instead of paying for coffees to lock in profits and/or avoid volatility. So you buy a shitcoin that makes you a 50x and pass it to stable coin just in case the price goes down as fast as it has risen.