Honestly I believe bitcoin is better since one you don't use your credit card so you don't loose you needed cash but instead your cash that you could easily earn back from mining. Plus, it's open to all ages unlike credit cards.
Yes, bitcoin has no boundary and will excel more than the other currencies, also cryptocurrencies have no exact value because of the active volatility. We all benefits on that.
I dont really think so, because anything that has an advantage also has disadvantage. Yes, bitcoin offers features that are way much better than what regular currencies can offer, but that doesnt place it on top, because you will always need regular currencies in most cases than bitcoin
They have different uses and importance, regular currency is what we still need to sustain our living, yet cryptocurrencies is much better for savings that can secure our future.