I think you hit the nail on the head there.  They can be complementary and definitely aren't mutually exclusive.  Having it as an asset makes the value of the currency more stable over time and the use as a currency (no matter the ratio of the two) keeps it flowing.  Eventually after another order of magnitude or two bitcoin and fiat will reach a more or less stable range where the main increase in bitcoin to fiat price will be due to whatever inflation that fiat has eating away its value.  So you might have $100 in bitcoin, but the next year it will be $103 due inflation of the dollar.  Then $106. etc    As compared to now where the value of bitcoin is increasing due to people realizing that it is a great way to preserve the value of the assets that you have earned over time, particularly as contrasted with fiat.  Now the value of bitcoin is increasing slightly due to inflation of fiat, but that increase is dwarfed by the other use cases and uptake as an asset class. 

Early adopters (and some say we are still early) are rewarded for their belief and constancy in supporting bitcoin over the last almost 16 years.  It is part of the virtuous cycle that is in the code.