Because the cappuccino will continue to cost them $4 tomorrow, next week and next month. Sure, its value changes and a cappuccino may even cost a different amount sometime in the future, but its easy to know the value of the money you have because the exchange rate between dollars and items in the shop doesn't change so much.

Contrast that with bitcoin, where the value often changes by many, many cappuccino's in a single day.

You can choose to become poor slowly or to get rich slowly. The short-term volatility doesn't matter in the long run.

In the long run we're all dead. Short-term volatility matters a lot given gambler's ruin etc.

Predictable inflation is a form of stability.

"I would choose a volatile 200% increase over a year than a stable predictable 10% decrease." Michael J. Saylor

Is this for an investment or a currency? There's a reason there is both.

Moderate inflation is a feature, not a bug, due to sticky wages [1]. Without inflation you get longer lasting recessions and worse unemployment. [1]: https://en.wikipedia.org/wiki/Nominal_rigidity