Bitcoin is digital money, so you can buy digital bananas with it.

For bitcoin transactions within 2-3 minutes you will not overpay x2 the cost of your bananas. The problem with bitcoin is not that no one will pay in bitcoin for goods, but that at the moment there are few sellers of goods (like your bananas) and services willing to accept btc as payment.

I have doubts at all that there will ever come a time when you can buy a cup of coffee with the help of bitcoin. I’ll voice an already hackneyed phrase, it’s like buying a cup of coffee for a bar of gold. Bitcoin has already become disproportionately big that it is unlikely to be used for purchases of small goods. Moreover, btc has been transformed into an investment tool from digital money. This is neither good nor bad, but it just happened and you need to accept it, and not be indignant.