Bitcoin is not for buying you meals and groceries. It is meant for business purposes. The value of cash is eaten away by inflation time after time. Bitcoin and other alternative cryptocurrencies fluctuate and have greater strength when it comes to business world. Due to its volatility, its price can rapidly increase or decrease. Both money, be it digital or paper, are useful. Let us not confuse ourselves with their purposes and roles.
Cash is the valid thing everywhere in the world. No problem for spending it especially for usd currency let's say. That's why it's better clearly.