Bitcoin is not possible to be the main currency. because indeed if we look at this it is not possible with fluctuating prices and also very risky. but with the blockchain later it can provide a new thing that might also be a digital payment option.
I agree with you that bitcoin will not be a major currency, because besides the price is not stable, there are still many countries with low levels of public education so that it would be difficult if using bitcoin. Besides that there are still many internet networks that are slow.
But if this is an alternative currency, I am sure it will be usable because this is a reasonable choice for middle and upper class people who have mastered technology and already established economic levels.
Bitcoin's value may not be stable due of fluctuation, still its tittle is dominant and persistent as a leading currency in crypto market. And we are aware about its fulfillment platform that shown huge potential. Also, some government adopt and take bitcoin licitly with individual perspection that behold on future's wealth.