You can buy a pizza with it, you just can't price a pizza in it. You can't build business model and then say, "if I change X BTC for my pizzas, I will be profit

You can buy a pizza with it, you just can't price a pizza in it. You can't build business model and then say, "if I change X BTC for my pizzas, I will be profitable," because a.) You can't anticipate the price and b.) Your obligations are priced in dollars (or whatever currency)